Screw conveyor is widely used in food packaging field. This paper puts forward a new kind of flexible blades of screw conveyor, to replace the traditional rigid helical blade. Based on the theory of compliant mechanism, the motion are analyzed when the flexible screw blade works. Based on the medium mechanics theory related, The interaction between flexible screw and material relations are analyzed, and the mathematical model of power consumption and transmission capacity are established. The work process of flexible screw working process is simulated with discrete element software EDEM. The result verified the theory is correct.