In order to overcome the bottleneck of electric mixer and achieve wide bandwidth signal mixing, a microwave photonic mixing scheme based on dual polarization double parallel Mach-Zehnder modulator is proposed. Carrier suppression single sideband modulation is achieved by adjusting six direct-currentbias voltages. Radio frequency(RF) and Local oscillator(LO) signals are injected into modulators separately, separated from each other and modulated separately. They are transmitted on two orthogonal polarization states. Finally, both of them are adjusted to the same polarization state by polarization controller and polarizerto beat the frequency. The switching of up-conversion and down-conversion only needs to change one of the direct-current bias voltages. The simulation and experiment results show that the scheme is feasible. When the RF frequency ranges from 11 GHz to 25 GHz, the RF spurious rejection ratio of the up-converted or down-converted signals output by the scheme is no less than 25 dB, and the spectrum purity is high and the tunability is good. The switching between the frequency conversion modes is convenient, the RF/LO isolation of the system reaches -49 dB.