Using CFD to simulate the flow field of impinging jet mixer in polyurea spraying gun,discussing the process of the spraying and jointing of the mixer after studying the profile of velocity and pressure.Spraying and jointing are available for the nozzle by changing the inlet pressure, the export velocity is slow under low pressure, so the outburst changes into a stream of flow and the jointing function is realized;while the export velocity is fast when the pressure is high,so the flow spray out to realize the spraying function.The distribution of the pressure and velocity within the mixer is extremely uneven,this is helpful for part A and part B mixing in the mixer.