The Radio Frequency(RF) front-end for the superconducting cavity of the high average power THz equipment is designed and implemented. By combining the signal source 8663A and the AD9858 Direct Digital Synthesizer(DDS), a signal with 30.72 MHz intermediate frequency and a local oscillator signal of 1 330.72 MHz are generated. The 30.72 MHz signal generated by the AD9858 is used as the reference signal of the clock board AD9510 for generating Analog to Digital Converter(ADC) and Digital to Analog Converter(DAC) driving sampling signal of 122.88 MHz and 245.76 MHz respectively. According to the measurement, the clock signal timing jitter is around 4 ps, the amplitude and phase of sampling error caused by the jitter is ±0.04% and ±0.025% respectively, which is in line with the design requirements.