A bandwidth extension method, comprising: acquiring a bandwidth extension parameter, wherein the bandwidth extension parameter comprises the following parameters: a linear predictive coefficient, LPC, line spectral frequency, LSF, parameters, an adaptive codebook contribution, and an algebraic codebook contribution; and performing, according to the bandwidth extension parameter, bandwidth extension on a decoded low frequency band signal, to obtain a high frequency band signal; wherein the performing, according to the bandwidth extension parameter, bandwidth extension on a decoded low frequency band signal, to obtain a high frequency band signal comprises: predicting a high frequency band gain according to the LPC; and when a decoding rate is not greater than a given value, predicting a high frequency band excitation signal by: calculating a difference value between each two LSF parameters to obtain a group of difference values of the LSF parameters; searching for a minimum difference value, determining a frequency bin according to the minimum difference value; and selecting a frequency domain excitation signal with a frequency band from a low frequency band excitation signal according to the frequency bin as the high frequency band excitation signal; and obtaining the high frequency band signal according to the high frequency band gain and the high frequency band excitation signal. acquiring a bandwidth extension parameter, wherein the bandwidth extension parameter comprises the following parameters: a linear predictive coefficient, LPC, line spectral frequency, LSF, parameters, an adaptive codebook contribution, and an algebraic codebook contribution; and performing, according to the bandwidth extension parameter, bandwidth extension on a decoded low frequency band signal, to obtain a high frequency band signal; wherein the performing, according to the bandwidth extension parameter, bandwidth extension on a decoded low frequency band signal, to obtain a high frequency band signal comprises: predicting a high frequency band gain according to the LPC; and when a decoding rate is not greater than a given value, predicting a high frequency band excitation signal by: calculating a difference value between each two LSF parameters to obtain a group of difference values of the LSF parameters; searching for a minimum difference value, determining a frequency bin according to the minimum difference value; and selecting a frequency domain excitation signal with a frequency band from a low frequency band excitation signal according to the frequency bin as the high frequency band excitation signal; and obtaining the high frequency band signal according to the high frequency band gain and the high frequency band excitation signal. predicting a high frequency band gain according to the LPC; and when a decoding rate is not greater than a given value, predicting a high frequency band excitation signal by: calculating a difference value between each two LSF parameters to obtain a group of difference values of the LSF parameters; searching for a minimum difference value, determining a frequency bin according to the minimum difference value; and selecting a frequency domain excitation signal with a frequency band from a low frequency band excitation signal according to the frequency bin as the high frequency band excitation signal; and obtaining the high frequency band signal according to the high frequency band gain and the high frequency band excitation signal.