Abstract: Simulation solutions to assistant nozzle with four orifice-form was done based on Fluent．The flow field velocity in the state of turbulence were obtained, and the inside flow field of assistant nozzle is microcosmically described．Influence of the orifice-form to the ejecting flow field was analyzed．According to the result of numerical calculation，supplied with the same air-pressure，the ejecting capacity of four orifice-form assistant nozzle took turns：7 circular orifice > rectangular orifice > circular twin-orifice > single circular orifice．Compared with the experiment result，it was proven that the numerical simulation has a high reliability．