The simulation results should be consistent with the actual situation of structure, when the finite element simulation software is used to analyze the structural strength. In order to reduce the influence of the simulation result, the simplified models should be identical with the structure. Throat-insert of a SRM nozzle is one of the most important parts, which compresses gas in the process of motor working. It is very important to make strength analysis on throat-insert of a SRM nozzle. In this paper, a throat-insert of SRM was taken as an example. Three structure finite element throat models were created and calculated by the Abaqus software, and the three simplified methods are commonly used in the strength analysis of SRM. At last, the strength results were compared and discussed. The results show that different simplified models may have a significant impact on the results. Therefore, the specific situation should be analyzed according to the particular request in the finite element simulation, in order to ensure the accuracy of calculation results.