Abstract: There exist high extrusion force and its inaccurate forecast in the extrusion process of an IN690 superalloy tube.After the flow function method was used to analyze the extrusion process and to construct a mathematical model of solving the extrusion force,the flow lines of the superalloy were presented in the stable extrusion state.The relationship between technological parameters and extrusion force of the IN690 superalloy tube was determined on the basis of studying the effects of extrusion temperature,friction coefficient and mold angle on the extrusion force.The extrusion temperature and mold angle were optimized by minimizing the extruding force.