A method for determining an optical signal power change, comprising: obtaining a first optical signal, wherein the first optical signal comprises a plurality of wavelength signals, the plurality of wavelength signals are distributed in a plurality of bands, different bands correspond to different wavelength signals, and each band comprises at least one wavelength signal of the plurality of wavelength signals; detecting an optical power of each band and a center wavelength signal of each band; obtaining a preset single-wavelength transmit power and a preset coefficient, wherein the preset coefficient is a power change coefficient of the first optical signal in transmission over an optical fiber; characterized in that the method further comprises the steps of: determining an equivalent quantity N of equivalent wavelength signals based on the optical power of each band and the preset single-wavelength transmit power, wherein a total power of the N equivalent wavelength signals is equal to a total power of the first optical signal; determining an equivalent wavelength signal corresponding to the first optical signal based on the optical power of each band and the center wavelength signal of each band, wherein a difference between a power change value of the N equivalent wavelength signals in transmission over the optical fiber and a first power change value of the first optical signal in the transmission over the optical fiber falls within a preset range; and determining a target power based on the preset coefficient, the equivalent wavelength signal, the equivalent quantity, and the preset single-wavelength transmit power, wherein the target power is used to compensate for the first power change value. obtaining a first optical signal, wherein the first optical signal comprises a plurality of wavelength signals, the plurality of wavelength signals are distributed in a plurality of bands, different bands correspond to different wavelength signals, and each band comprises at least one wavelength signal of the plurality of wavelength signals; detecting an optical power of each band and a center wavelength signal of each band; obtaining a preset single-wavelength transmit power and a preset coefficient, wherein the preset coefficient is a power change coefficient of the first optical signal in transmission over an optical fiber; characterized in that the method further comprises the steps of: determining an equivalent quantity N of equivalent wavelength signals based on the optical power of each band and the preset single-wavelength transmit power, wherein a total power of the N equivalent wavelength signals is equal to a total power of the first optical signal; determining an equivalent wavelength signal corresponding to the first optical signal based on the optical power of each band and the center wavelength signal of each band, wherein a difference between a power change value of the N equivalent wavelength signals in transmission over the optical fiber and a first power change value of the first optical signal in the transmission over the optical fiber falls within a preset range; and determining a target power based on the preset coefficient, the equivalent wavelength signal, the equivalent quantity, and the preset single-wavelength transmit power, wherein the target power is used to compensate for the first power change value. determining an equivalent quantity N of equivalent wavelength signals based on the optical power of each band and the preset single-wavelength transmit power, wherein a total power of the N equivalent wavelength signals is equal to a total power of the first optical signal; determining an equivalent wavelength signal corresponding to the first optical signal based on the optical power of each band and the center wavelength signal of each band, wherein a difference between a power change value of the N equivalent wavelength signals in transmission over the optical fiber and a first power change value of the first optical signal in the transmission over the optical fiber falls within a preset range; and determining a target power based on the preset coefficient, the equivalent wavelength signal, the equivalent quantity, and the preset single-wavelength transmit power, wherein the target power is used to compensate for the first power change value.