Abstract: Aiming at the measurement of photoelastic modulator (PEM) in ultra-high speed full polarization field, a circular PEM with target frequency near 100 kHz was studied, which was composed of an elastic-optic crystal and two piezoelectric actuators with azimuth difference of 45°. The resonant frequency of the elastic-optic crystal and the vibration frequency of the piezoelectric actuators were calculated theoretically. When the two frequencies were consistent, the PEM worked in the resonant state, and the modulation efficiency of PEM reached the highest. When the PEM reached the resonant state and tended to be stable, the amplitude and phase of the driving voltage of the two piezoelectric actuators were adjusted to achieve two special modulation modes of pure standing wave mode and pure traveling wave mode. The pure standing wave mode could realize the delay and azimuth of the modulated fast axis under pure electric control, and the pure traveling wave mode could realize the high-speed rotation of the modulated fast axis under pure electric control at the half-frequency speed of the PEM resonant frequency. Finally, the COMSOL finite element simulation was used to simulate the two modulation modes of PEM, and the vibration mode and fast axis direction of PEM in two modulation states were verified. It shows that the PEM can realize multifunctional elastic-optic modulation, which provides theoretical support for the subsequent field of light polarization.