The numerical model for the wake field of a solid rocket motor (SRM) after ignition is established, and the distribution of the high speed gas jet along the axial and radial direction of the SRM are all analyzed and compared with the experimental infrared image. The results demonstrate that the jet velocity, pressure and temperature are fluctuating greatly at the outlet of the nozzle. The pressure near the nozzle along the radial direction was firstly decreased and then increased, and with the increase of distance from the nozzle exit, the pressure is reduced monotonously. At the boundary of the jet shear layer, the attenuation gradient of the radial velocity increases, and the peak pressure is greater near the exit of the nozzle at 2 m.