The digital design method of time gain control model is a very important part of digital design in the underwater active sound detection system. In the context of analyzing the sound signal sent by the transmitter to the transmitter, the signal received by the receiving switch to the receiving transformer will have a useful signal, reverberation, and noise. The basic principles of time gain compensation will be introduced. Simulink platform, using digital modeling design methods, time gain control to compensate the signal gain, and build a time gain control universal model. The simulation verification is performed through the model, and the results can be better restored to useful signals.