In order to tail-pipe nozzle of solid rocket motor design and improvement of the thermal protection provide a theoretical basis and a useful reference, based on the anatomy of wreckage of a solid rocket motor's tail-pipe nozzle, inside lining of tail-pipe nozzle was measured and analyzed, given the ablation law of inside lining. Tail-pipe nozzle flow field is calculated and analyzed by using the method of flow field simulation. That analyzed ablation mechanism of tail-pipe nozzle inside lining; the analysis shows that condensed particle erosion is main reason for local serve ablation of tail-pipe nozzle inside lining.