A high precision frequency conversion technology based on microwave photonic link is introduced, which is based on modulation and processing of microwave photonics signal. Radio frequency signal is converted into optical signal by electro-optic conversion, and the frequency is converted up and down through optical filter and acousto-optic frequency shift. Finally high-precision frequency conversion signal is obtained. The system can shift the frequency of RF signal within ±2 MHz in the range of 20 GHz, and the maximum accuracy can reach 100 Hz. Benefiting from the high bandwidth, real-time and high precision of microwave photonic link, the technique can perform high precision real-time frequency conversion of high frequency radio frequency signal in optical domain to overcome frequency limitation and achieve fine frequency regulation of radio frequency signal.