Aiming at the abnormal phenomena in the flight test of a micro solid rocket motor, the simulation research was carried out from two aspects of support frame melting and high temperature particle deposition. In the test, the thrust eccentric angle is 0. 26° when the stiffener of the support frame is melted by 3/8. The deposition of high temperature particles in the throat of the nozzle will increase the thrust eccentric angle, and the larger the deposition thickness is, the larger the thrust eccentric angle is, and the thrust eccentric angle reaches 0.7° when the deposition thickness is 0.75 mm. Based on this, by replacing the support frame material with non-ablative molybdenum alloy material, and using HTPB propellant without metal particles in the combustion chamber, the generation of high-temperature particles was reduced, and the motor design was optimized and verified by experiments. The simulation results show that the test debris and flight test curves of the nozzle in this study show that the improvement measures are effective, which provides a basis for the design of micro engines.