A supervisory and control system for oil tanks area based on PLC S7-300 and configuration software Force-Control is introduced in this paper. The hardware structure of the system and the software design are both described in detail. In this system, Superior computers communicate with PLC through Industrial Ethernet. The superior computers system adopts duplex redundancy and the PLC adopts software redundancy. This monitoring system integrates the merit of PLC and computer and improves the reliability.