The effect of mass unbalanced moment under high-frequency vibration of a helicopter on the performance of a photoelectrical stabilized platform was discussed. A system model based feedforward compensation method for mass unbalanced moment was proposed on the basis of a three closed-loop control system with current feedback, velocity feedback and position feedback on the traditional photoelectrical stabilized platform. By calibrating the mass eccentricity of the platform, the acceleration signals of the platform were obtained by a acceleration sensor to perform the feedforward compensation to suppress the mass unbalanced moment of the platform. The experiment results show that the disturbance isolation increases at least 6.4 dB after inducing the feedforward compensation system as compared with that of the traditional three closed-loop control system. Moreover, as compared with that of compensation scheme using a disturbance observer, the proposed photoelectrical stabilized platform system with the feedforward compensation not only increases its compensation ability about 12.9 dB at low-frequency, but also overcomes the problems that disturbance observer can not compensate mass unbalanced moment at high-frequency. It increases greatly the disturbance isolation at full frequencies, allows the visual axis to better keep in an inertial space and shows high practical values.