The precision of traditional mass and gravity center measure method is relatively low and the system fault tolerance is not high. This paper presents a high precision redundant measure method for mass and gravity center. The method could make on-line calibration for the measurement unit, and the software could automatically select the calibration coefficient with respect to the measurement value of sensors to correct the mass and gravity center value, so as to eliminate the nonlinear error of the sensors. The software can automatically compensate the measurement result of the gravity center according to the installation error of the payload so that the misalignment and deflection effect of installation can be reduced and the measurement accuracy of the mass and gravity center can be improved. The system reliability is enhanced based on the realization of cross redundancy through the hardware system’s redundant design and the software system data sharing. The method has passed the actual tests, its mass measurement error is better than 0.05%, and its gravity center measurement error is less than ±1mm, at the same time the mass and gravity center redundancy switching function of the system has been verified.