In order to explore a simple and effective technical approach to the temperature field of solid rocket motor grain under variable ambient temperature, the grain temperature field of a solid rocket motor under temperature circulating test was studied by means of finite element heat transfer analysis.Two-dimension and three-dimension heat transfer models were established for different grain structures.By comparing the calculated results with the test results, the two-dimensional heat transfer method can improve the calculation efficiency of the grain temperature field, and the calculation results are in good agreement with the test results, which can meet the test prediction requirements.Therefore, in the engineering analysis, in order to obtain the effective analysis results quickly, the two-dimensional heat transfer model can be used to analyze the grain temperature field of solid rocket motor.The two-dimensional non-fin grain model is suitable for simulating the temperature field of the grain far away from the fin, and the two-dimensional fin-having grain model is suitable for simulating the temperature field near the grain fin.