Abstract: To meet the control requirement of the amplitude, phase, frequency, auto-startup logic, interlock and online parameter modification of the cyclotron RF system, the general hardware and software of low level radio frequency (LLRF) system were proposed. The hardware of the system was based on ZYNQ FPGA and high-speed ADC and DAC. The digital down-conversion was adopted to implement the amplitude, phase, and tuning control and a digital circuit was designed to detect the spark in the cavity. The performance of amplitude control is 0.015% and the performance of phase control is 0.04°. The system takes full advantage of the ability of all-programmable of the digital LLRF system and can be used on multiple cyclotrons by changing the parameters on the PC software.