This paper

according to China's current production of plastic extrusion

proposes the optimized process parameters based on expert system to retrofit the existing control system. It also introduces the composition of expert system

manmachine interface

the establishment of information base

the design of inference machine and selflearning machine. By Visual Prolog

an expert system programmed language

the expert system configured with plastic extruder process parameters is finally realized with the required values of process parameters. Hence

it replaces the manual setting of process parameters by engineers

saves labor costs as well as improves automation and production efficiency.