Abstract: LEAF(Low Energy high intensity highly charged ion Accelerator Facility) built by the Institute of Modern Physics, Chinese Academy of Sciences, is a high intensity highly charged heavy ion linear accelerator complex for multi-discipline researches such as low energy nuclear astrophysics, atomic physics, material irradiation physics, etc. The main part of the LEAF accelerator is a 4-vane RFQ. To achieve stable control of the cavity frequency, Radio Frequency (RF) amplitude and phase, the RF control system uses the scheme of digital low levels. According to the special requirements of LEAF-RFQ, this low-level system develops unique functions such as automatic frequency tracking, dual port drive for high power RF amplifier, and rapid phase switching of mixed ion beams, and realizes stable beam commissioning. Meanwhile, the one-click automatic RF power loading and closed loop of the cavity are realized by using the code development.