A method for self-adaptation of ranks of Multi-Input Multi-Output, MIMO, channels comprising: a base station receiving ranks reported by a user equipment via a rank receiving window, determining a rank at the current moment based on a distribution state of each rank in the rank receiving window at the current moment, and determining the number of independent channels used for sending downstream data to the user equipment based on the rank at the current moment, characterized in that in the step of determining the rank at the current moment: when the number of ranks in the rank receiving window is greater than a threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 2, the base station takes a rank newly reported by the user equipment in the rank receiving window as the rank at the current moment; wherein state 2 means that: when the smallest value N max S among the number of receiving antennas and the number of transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions: the ranks in the rank receiving window in turn are continuous x and continuous y, where values of x and y differ by 1, and the number of y is greater than or equal to the number of x; or when N max S is equal to 8, distribution of each rank in the rank receiving window meets the following conditions: the ranks in the rank receiving window in turn are continuous x, continuous y and continuous z, where difference values of x, y, z in turn are 1, values of x, y, z in turn increase or decrease, and the total number of y and z is greater than or equal to the number of x, and the number of z is greater than or equal to the number of y. when the number of ranks in the rank receiving window is greater than a threshold A and the distribution state of each rank in the rank receiving window at the current moment is state 2, the base station takes a rank newly reported by the user equipment in the rank receiving window as the rank at the current moment; wherein state 2 means that: when the smallest value N max S among the number of receiving antennas and the number of transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions: the ranks in the rank receiving window in turn are continuous x and continuous y, where values of x and y differ by 1, and the number of y is greater than or equal to the number of x; or when N max S is equal to 8, distribution of each rank in the rank receiving window meets the following conditions: the ranks in the rank receiving window in turn are continuous x, continuous y and continuous z, where difference values of x, y, z in turn are 1, values of x, y, z in turn increase or decrease, and the total number of y and z is greater than or equal to the number of x, and the number of z is greater than or equal to the number of y. when the smallest value N max S among the number of receiving antennas and the number of transmitting antennas is greater than or equal to 2 and is less than or equal to 7, distribution of each rank in the rank receiving window meets the following conditions: the ranks in the rank receiving window in turn are continuous x and continuous y, where values of x and y differ by 1, and the number of y is greater than or equal to the number of x; or when N max S is equal to 8, distribution of each rank in the rank receiving window meets the following conditions: the ranks in the rank receiving window in turn are continuous x, continuous y and continuous z, where difference values of x, y, z in turn are 1, values of x, y, z in turn increase or decrease, and the total number of y and z is greater than or equal to the number of x, and the number of z is greater than or equal to the number of y.