Laser cutting process to achieve high-energy laser beam is a result of the interaction and auxiliary gas, the nozzle shape and the resulting flow field characteristics that affect the quality and efficiency of laser cutting a key factor. Axisymmetric compressible fluid under the N-S equations, using a structured grid and second-order accuracy finite volume method, analysis of laser cutting assisted supersonic gas jet nozzle and the nozzle throat field structure of the relationship between the corner and to study the length of flow field divergence Duan the state parameters of the law, through reasonable planning and divergence angle throat lengths, using a small slash instead of a complex curve segment to simplify the structure of a supersonic nozzle. The simulation results show that the structure will receive a reasonable auxiliary gas outlet nozzle parameters and dynamics of the jet field structure with good performance.