A photonic microwave phase-shifting system with continuously tunable phase shift and the frequency multiplication factor is proposed. Without optical filters, the scheme is mainly consists of two integrated dual-polarization dual-parallel Mach-Zehnder modulators. By adjusting voltages of the radio frequency driving signal and direct current bias signal on the dual-parallel Mach-Zehnder modulators and phase modulator, frequency-doubling or frequency-tripling, ..., frequency-sextupling microwave signal can be generated, with 0° to 360℃ontinuously tunable phase shift. The simulation results show that, when the radio frequency signal frequency is 10 GHz, the output microwave signals with the frequency 20, 30, 40, 50, 60 GHz can be obtained respectively. The ratio of direct current bias voltage and half-wave voltage of the phase modulator is set to vary from 0 to 1, corresponding to phase shift of microwave signal vary from -180° to 180°. In addition, the effects of the extinction ratio of the modulators on the optical sideband suppression ratio and electrical spurious suppression ratio of the output microwave signal, as well as the effects of the phase balance of the 90° hybrid coupler on the phase drift and amplitude variation of the microwave signal are analyzed.