A method for transmitting Channel State Information CSI from a user station to an access point, comprising: Calculating m H (k) the maximum value in real part and imaginary part of each element in CSI matrix H eff ( k), wherein k is a position parameter of the sub-carrier; Carrying out M bit quantization of m H ( k) to obtain the quantization amplitude M H ( k); M is positive integer; Calculating the linear portion M H lin k of M H ( k); Carrying out N b bit quantization of real part and imaginary part of each element in H eff ( k) respectively by M H lin k, to obtain the quantized CSI matrix M eff q k; N b is positive integer; Transmitting said quantization amplitude M H ( k) and said quantized CSI matrix M eff q k. characterized in that, carrying out Mbit quantization of m H ( k), comprising: M H k = min 2 M − 1, f g m H k; Wherein, M H (k) is used for taking the minimum value between (2 M -1) and f ( g(m H ( k))); the function f ( g ( m H ( k))) indicates the round operation of the calculation result of g ( m H ( k)); g ( m H ( k))=max(0, a ·log b ( m H ( k)+ c)); Wherein, a, b and c are positive real numbers, Using the equation H H lin k = b M H k / a to calculate the linear portion M H lin k of M H ( k); or characterized in that: using M H lin k to carry out N b bit quantization to real part and imaginary part of each element in H eff ( k) respectively, comprising: H eff m l q R = sign H eff m l k * min 2 N b − 1 − 1, round Re H eff m l k M H lin k − c 2 N b − 1 − 1; H eff m l q I = sign H eff m l k * min 2 N b − 1 − 1, round Im H eff m l k M H lin k − c 2 N b − 1 − 1; Wherein, H eff ( m,l) ( k) indicates the element in H eff ( k); H eff m l q R indicates the real part of quantized H eff ( m,l) ( k); H eff m l q I k indicates the imaginary part of quantized H eff ( m,l) ( k); m is line position parameter, l is column position parameter; sign ( H eff ( m,l) ( k)) indicates the sign polarity at H eff ( m,l) ( k); min 2 N b − 1 − 1, round Re H eff m l k M H lin k − c 2 N b − 1 − 1 indicates the minimum value between (2 N b -1 -1) and round Re H eff m l k M H lin k − c 2 N b − 1 − 1; round indicates the round operation; "∥" indicates absolute operation; c is positive real number. Calculating m H (k) the maximum value in real part and imaginary part of each element in CSI matrix H eff ( k), wherein k is a position parameter of the sub-carrier; Carrying out M bit quantization of m H ( k) to obtain the quantization amplitude M H ( k); M is positive integer; Calculating the linear portion M H lin k of M H ( k); Carrying out N b bit quantization of real part and imaginary part of each element in H eff ( k) respectively by M H lin k, to obtain the quantized CSI matrix M eff q k; N b is positive integer; Transmitting said quantization amplitude M H ( k) and said quantized CSI matrix M eff q k. characterized in that, carrying out Mbit quantization of m H ( k), comprising: M H k = min 2 M − 1, f g m H k; Wherein, M H (k) is used for taking the minimum value between (2 M -1) and f ( g(m H ( k))); the function f ( g ( m H ( k))) indicates the round operation of the calculation result of g ( m H ( k)); g ( m H ( k))=max(0, a ·log b ( m H ( k)+ c)); Wherein, a, b and c are positive real numbers, Using the equation H H lin k = b M H k / a to calculate the linear portion M H lin k of M H ( k); or characterized in that: using M H lin k to carry out N b bit quantization to real part and imaginary part of each element in H eff ( k) respectively, comprising: H eff m l q R = sign H eff m l k * min 2 N b − 1 − 1, round Re H eff m l k M H lin k − c 2 N b − 1 − 1; H eff m l q I = sign H eff m l k * min 2 N b − 1 − 1, round Im H eff m l k M H lin k − c 2 N b − 1 − 1; Wherein, H eff ( m,l) ( k) indicates the element in H eff ( k); H eff m l q R indicates the real part of quantized H eff ( m,l) ( k); H eff m l q I k indicates the imaginary part of quantized H eff ( m,l) ( k); m is line position parameter, l is column position parameter; sign ( H eff ( m,l) ( k)) indicates the sign polarity at H eff ( m,l) ( k); min 2 N b − 1 − 1, round Re H eff m l k M H lin k − c 2 N b − 1 − 1 indicates the minimum value between (2 N b -1 -1) and round Re H eff m l k M H lin k − c 2 N b − 1 − 1; round indicates the round operation; "∥" indicates absolute operation; c is positive real number. Wherein, M H (k) is used for taking the minimum value between (2 M -1) and f ( g(m H ( k))); the function f ( g ( m H ( k))) indicates the round operation of the calculation result of g ( m H ( k)); g ( m H ( k))=max(0, a ·log b ( m H ( k)+ c)); Wherein, a, b and c are positive real numbers, Using the equation H H lin k = b M H k / a to calculate the linear portion M H lin k of M H ( k); or characterized in that: using M H lin k to carry out N b bit quantization to real part and imaginary part of each element in H eff ( k) respectively, comprising: H eff m l q R = sign H eff m l k * min 2 N b − 1 − 1, round Re H eff m l k M H lin k − c 2 N b − 1 − 1; H eff m l q I = sign H eff m l k * min 2 N b − 1 − 1, round Im H eff m l k M H lin k − c 2 N b − 1 − 1; Wherein, H eff ( m,l) ( k) indicates the element in H eff ( k); H eff m l q R indicates the real part of quantized H eff ( m,l) ( k); H eff m l q I k indicates the imaginary part of quantized H eff ( m,l) ( k); m is line position parameter, l is column position parameter; sign ( H eff ( m,l) ( k)) indicates the sign polarity at H eff ( m,l) ( k); min 2 N b − 1 − 1, round Re H eff m l k M H lin k − c 2 N b − 1 − 1 indicates the minimum value between (2 N b -1 -1) and round Re H eff m l k M H lin k − c 2 N b − 1 − 1; round indicates the round operation; "∥" indicates absolute operation; c is positive real number.