An intelligent platform based on RS485 bus was created. It takes the sectional-control theory which combines the PID algorithm with fuzzy control theory as the strategy and integrates the crop growth and cultivation expert system. The system real-timely measures the environment factors in greenhouse and analyzes them to make decision and control the output devices so as to create the optimal grow environmental conditions in greenhouse. The application shows that the sectional-control algorithm makes the output trace the set value correctly and the distributed and unit module structure make the maintenance easier and lower the running cost.