Abstract: A signal processing system and method for a radiation detector based on a metal oxide semiconductor (MOS) transistor are disclosed. The signal processing system includes a power supply generation module, an analog signal processing module, and a digital signal acquiring-processing module. The power supply generation module provides a novel power supply method, and converts a positive high voltage power supply into a negative high voltage power supply to supply power to a last dynode of a photomultiplier tube (PMT). The analog signal processing module converts a negative current pulse signal into a voltage difference signal. The digital signal acquiring-processing module acquires a signal of the analog signal processing module, and converts the signal into a digital signal for identification.