A reconfigurable microwave photonic mixing and phase shifting system is proposed. By adjusting the frequency of the local oscillator signal and the angle of the polarizer, it can output up/down conversion microwave signal, and its phase can be adjusted continuously within 360°. In addition, by appropriately changing the phase difference between any two mixing channels, it can be reconstructed to realize I/Q mixing, double-balanced mixing and image rejection mixing. When applied to multiple channels, it can output multi-band mixing and phase-shifted microwave signal, and the phase of each channel can be adjusted independently. Since the high-order sidebands of the local oscillator signal are involved in the mixing, the requirements for the frequency of the local oscillator signal are reduced exponentially. The simulation results show that when the frequency of the local oscillator signal and the RF signal are 10 GHz and 19 GHz respectively, the mixing range of the system is 1~79 GHz, the phase shift amplitude difference is less than 0.1 mV, the image rejection ratio exceeds 65 dB, and the signal power difference after multi-band mixing is less than 0.2 dB. In addition, the 90° electrical phase shifter and polarization controller angle adjustment deviation hardly affect the system performance, and the appropriate radio frequency signal power can help improve the system performance. Theoretical analysis and simulation have verified that the system has high flexibility, reconfiguration and practicability.