In order to provide numerical value for the experiment design and analysis of the home-made ablation experimental system, a computational fluid dynamics(CFD) software FLUENT was successfully used to simulate speed field and temperature field of flame and particles of the ablation spray gun( the key part of the system). The mathematic model of gas-solid flow was founded from basic theory of twophase flow and transport equation. Dynamics flight behavior of spray particles was computed by random orbit model in discrete phase mode. The change rule of speed field and temperature field of flame and particles were known. The results show that the numerical method can achieve better simulation for the two-phase flow.