Abstract: This paper puts forward a new layered co-ordination expert system structure with a view to improving knowledge management and the speed for making decision,At the same time,an area optimization(AO)thought is provided to solve engineering optimiza-tion problem as better as possible.These methods are used to actually build an urea process expert system with optimal control,fault diagnosis and performance prediction. Part of software has been implemented in an urea factory with satisfying results.