The ADS Injector II is a linear superconducting accelerator, which is made up of the four vane type RFQ, MEBTand superconducting cavities. The amplitude and phase stability of all RF resonant cavities need to be controlledprecisely by the low level radio frequency (LLRF) control system. Fig. 1 is the block diagram of the LLRF controlsystem, which is composed of the RF synchronous signal distributor, LLRF system and solide state RF high poweramplifier.