According to the round jet flow condition, the computational fluid dynamics (CFD) model of the flow field is established, and the numerical simulation of the flow characteristics of the turbulent jet external flow field is carried out by use CFD of finite element software ANSYS. By disturbing the boundary layer that was in a laminar state by exerting impulse micro-jet at the entrance of the external flow field, the simulation results were gotten. Then the variation characteristics of the external flow field were analyzed under the influence of radially micro-jet. The external flow field characteristics at different frequency of pulses were gotten under the changing conditions of the frequency of micro-jet. By contrast the results, the numerical simulation results of jet flow field have the same trend with the experimental result, and they are accord with the results of the previous experiments.