A method for predicting a high frequency band signal, comprising: acquiring a signal type of an audio signal and a low frequency band signal of the audio signal; obtaining a frequency envelope of each subband of a high frequency band signal of the audio signal according to the signal type, wherein the high frequency band signal of the audio signal comprises multiple spectrum coefficients, the multiple spectrum coefficients are classified into multiple subbands, each of the multiple subbands comprises multiple spectrum coefficients, and a frequency envelope of a subband is calculated based on the spectrum coefficients of the subband; and sending a bitstream that carries the signal type, and encoding indices of the low frequency band signal and the frequency envelopes of the subbands of the high frequency band signal; wherein the signal type is a harmonic signal or a non-harmonic signal, and the obtaining a frequency envelope of each subband of a high frequency band signal of the audio signal according to the signal type comprises: calculating the frequency envelope of the subband of the high frequency band signal by using a first quantity of spectrum coefficients when the signal type is a non-harmonic signal; or calculating the frequency envelope of the subband of the high frequency band signal by using a second quantity of spectrum coefficients when the signal type is a harmonic signal, characterized in that the second quantity is greater than the first quantity, and that a width of a subband covered by a frequency envelope that is of a high frequency band signal and is corresponding to a harmonic signal is wider than that covered by a frequency envelope that is of a high frequency band signal and is corresponding to a non-harmonic signal. acquiring a signal type of an audio signal and a low frequency band signal of the audio signal; obtaining a frequency envelope of each subband of a high frequency band signal of the audio signal according to the signal type, wherein the high frequency band signal of the audio signal comprises multiple spectrum coefficients, the multiple spectrum coefficients are classified into multiple subbands, each of the multiple subbands comprises multiple spectrum coefficients, and a frequency envelope of a subband is calculated based on the spectrum coefficients of the subband; and sending a bitstream that carries the signal type, and encoding indices of the low frequency band signal and the frequency envelopes of the subbands of the high frequency band signal; wherein the signal type is a harmonic signal or a non-harmonic signal, and the obtaining a frequency envelope of each subband of a high frequency band signal of the audio signal according to the signal type comprises: calculating the frequency envelope of the subband of the high frequency band signal by using a first quantity of spectrum coefficients when the signal type is a non-harmonic signal; or calculating the frequency envelope of the subband of the high frequency band signal by using a second quantity of spectrum coefficients when the signal type is a harmonic signal, characterized in that the second quantity is greater than the first quantity, and that a width of a subband covered by a frequency envelope that is of a high frequency band signal and is corresponding to a harmonic signal is wider than that covered by a frequency envelope that is of a high frequency band signal and is corresponding to a non-harmonic signal. calculating the frequency envelope of the subband of the high frequency band signal by using a first quantity of spectrum coefficients when the signal type is a non-harmonic signal; or calculating the frequency envelope of the subband of the high frequency band signal by using a second quantity of spectrum coefficients when the signal type is a harmonic signal, characterized in that the second quantity is greater than the first quantity, and that a width of a subband covered by a frequency envelope that is of a high frequency band signal and is corresponding to a harmonic signal is wider than that covered by a frequency envelope that is of a high frequency band signal and is corresponding to a non-harmonic signal.