A signal processing system includes n paths of load modulation modules and a combination module, where the n paths of load modulation modules are connected in parallel, an output end of each path of the load modulation modules is connected to an input end of the combination module, and n is an integer greater than 1; the n paths of load modulation modules include one path of main power amplification module and (n−1) paths of auxiliary power amplification modules, and the auxiliary power amplification modules are turned on when power values of signals received by input ends of the load modulation modules are greater than a first threshold; and the main power amplification module includes two outphasing power amplification units, and each path of auxiliary power amplification module includes two outphasing power amplifier arrays or one digital polar power amplifier array.