Embodiments of the present invention disclose an optical signal compensation device, where, a nonlinear compensation module in the optical signal compensation device adopts a new nonlinear compensation algorithm to perform nonlinear compensation on an optical signal, and during the process of performing the nonlinear compensation, it is no longer required to look up a table. Technical solutions provided in the embodiments of the present invention can effectively increase the processing speed of the nonlinear compensation, thereby reducing the overall processing delay of an optical signal compensation system.