In recent years, the real-time kinematic (RTK) high-precision satellite positioning technology with carrier phase difference technology as the core has developed rapidly in the field of surveying and mapping. This article is based on the RTK positioning principle, aiming at light and miniaturization, high precision, stable and fast satellite positioning receivers, the focus is on multi-system and multi-band Global Navigation Satellite System (GNSS) signal processing technology, including the GNSS multi-frequency RF front-end processing and baseband signal processing key technologies of the UAV RTK receiver. Through professional simulation methods, it can be concluded that the designed RF front-end receiving sensitivity is higher than -130dBm. The execution time for searching and capturing 6758 sampling points is only 0.68s, and the capture frequency shift error is about 0.932% of the Doppler frequency shift, and the frequency error after the GNSS signal carrier tracking stabilizes is basically concentrated below 0.75KHz. The simulation results show that the designed GNSS signal processing module meets the requirements of the actual multi-frequency RTK positioning receiver.