Based on a convergent nozzle and a conical nozzle, the simulation of the free jet of assemble nozzles by adopting a three-dimensional axial symmetrical model is presented in the paper. The study reveals the effect of cone angle of conical nozzle and the parabola equation of convergent nozzle on flow field by adjusting nozzles’ interior figure parameters. The distribution of pressure and velocity of gas jet are shown in the investigation. A conical nozzle with cone angle of 30° and a convergent nozzle described by the parabola equation of y=0.207x2 are designed and produced for the laser cutting experiment. Numerical simulation and experimental results are given at the end of the paper.