Abstract: The resonant frequency of the high intensity proton RFQ accelerator at the Institute of High Energy Physics is 352.2 MHz, and the control precision of the accelerating field is ±1% in amplitude and ±1° in phase, respectively. In order to accomplish these requirements, a digital low-level RF(LLRF) control system is adopted. This system includes three parts: the accelerating field amplitude and phase control, the cavity resonant frequency control and the high power interlock protection. The down-conversion of the cavity sampling signal and the up-conversion of the feedback excitation signal are realized by the analog devices. The real time feedback control of amplitude and phase adopts digital I/Q demodulation, and is assembled in a FPGA block, where three DSP blocks are used for communic