Abstract: In this paper,making use of the law of conservation of energy ,the variation of heat energy and power in the single screw extruder with self-heating was analyzed and a kind of calculating formula about transporting the heat and power was put forward. According to the formula, it provided the relationship between the power consumption of the productivity unit and parameters of material, the productivity and speed of screw, the length of screw, screw diameter. It provided a way to solve the problems for qualitative analysis in the design and use of single-screw extruder.