Based on melt spinning dynamic model and theory, a basic model of superfine denier polyester multifilament was established. Besides the expressions of quench air temperature and quench air velocity for superfine denier filament spinning process have been established in this paper. In different conditions of diameters of spinneret holes, spinning temperature and the quenching process, the degree of orientation, crystallinity and spinning stress of polyester filament in the spinning process was simulated, respectively. The variation of quench air temperature and air velocity of multifilament in different circles of spinneret was mainly discussed. The research was expected to provide basic theory for optimizing production technique and manufacturing high quality superfine denier polyester filament.