The invention discloses a multifunctional microwave photon module, which comprises a dual-polarization dual-parallel Mach-Zehnder modulator, a polarization controller, a polarization beam splitter anda balance photoelectric detector. The output end of the dual-polarization dual-parallel Mach-Zehnder modulator is connected with the input end of the polarization beam splitter through the polarization controller, and the two output ends of the polarization beam splitter are connected with the two input ends of the balance photoelectric detector respectively. The invention further discloses a signal processing method and device based on the multifunctional microwave photon module. The relative intensity noise in the microwave photonic link is effectively suppressed from the outside of the laser, various kinds of processing such as frequency mixing, frequency doubling and phase shifting can be carried out on microwave signals, the structure is simple, and the implementation cost is low.