To achieve the transient flow characteristics at exit orifice of nozzle on gasoline engine, two phase Euler-Euler schemes was used to simulate the internal flow of the swirl nozzle. Different nozzle configurations were studied. Cavitation and swirl flow occur in nozzle during the needle lift process. Larger tangential angle configuration of swirl slots generated larger degree cavitation and mean injection velocity, but its discharge coefficient in nozzle was slight smaller than that of small swirl slot. Turbulence kinetic energy changed with the time of cavitation occurring. Before the appearance of cavitation, larger swirl tangential angle generate more turbulence kinetic energy. After that moment, turbulence kinetic energy decreased with the fluid phase volume fraction reducing. Along nozzle injection hole length, turbulence kinetic energy obviously varied. Considering the affection of injection pressure on the flow characteristics, it led to significant changes in turbulence kinetic energy and mean injection velocity and affected a little on cavitation to this studied nozzle. These flow characteristics are as input for next spray simulation. They also apply design reference for injection nozzle.