Opto-eletrical stabilization/tracking device has the precision request to improve the stabilization/tracking accuracy due to its wide use on mobile measurement. The paper firstly sums up the error sources based on the system principle of stabilization and tracking, and expatiates the effect of some error items including disturbance moment, geometrical error, and assembling error of gyro etc. Furthermore, according as the probability theory, the paper expresses the comprehensive accuracy uniformly, and obtains the evaluation method of device accuracy. Finally, it gives the example of evaluation on the direct stabilization/tracking device. The research may be useful to the error estimation during system’s design phase, but also system optimization of performance, error compensation.