Considering the drawback of checking method indoor for the dynamic characteristics of tracking systems of photoelectric theodolites, a novel approach is proposed to evaluate the tracking performance of photoelectric theodolites in this paper.The equivalent mathematical model of tracking error of a photoelectric theodolite is established.On the basis of identification theory,the equivalent sine signal is inputted to the equivalent model, and then the output signals are processed to evaluate the tracking performance.The principle of the equivalent model of tracking error and the identification method of equivalent model order are introduced, and the design approach of equivalent sine signal is given according to the checking and testing desires of theodolites.Because the dynamic characteristics of the theodolite need to be inspirited fully by input signals to obtain accurate parameters of equivalent model, the frequency of dynamic target is modulated continuously.The proposed equivalent model is verified by simulation and experiments, obtained results indicate that the estimate errors of equivalent model including average error, maximum error and standard error are (2.587 2×10-6)°≈0°, 1.8″ and 1.1″,respectively,which shows that the equivalent model meets the needs of evaluating the tracking performance of theodolites, and achieves the accurate evaluation of tracking performance.