Abstract: In order to turn the pulp in the pressure screen turn into the slot more easily and to improve the screening ability， the vortex near the contoured slot should be reduced or eliminated. The local flow field model of the screen slot was drawn with UG software， and then the flow field model was simulated with FLUENT software. Different improvements of the contoured slot shape were analyzed， and finally the detail distribution contours of the pressure， turbulent kinetic energy and velocity magnitude in the contoured slot field were obtained. The results showed that in the experimental condition the larger the screen slot chamfering angle was， the smoother the fluid flow near the screen slot was. When chamfering angle radius increased to 04 mm， the vortex disappeared. When the chamfering angle radiuses of the contoured slot entrance on both sides were 05 mm， the pulp flow form was the best， the passage ratio was the largest and improved 124 ％ higher than before.