Abstract: The control system upgrade of the 320 kV heavy ion multidisciplinary research facility was studied in this paper. The upgraded control system was based on distributed system model. Serial port server, programmable logic controller (PLC) and servo motors were used to control and monitor all devices remotely. By building up EPICS IOC dynamic database, all controlled devices were integrated together seamlessly. As to operator interface, control system studio (CSS) toolkit was adopted to access all controlled devices transparently. This upgraded control system has been running for more than 10 000 h. At present, the control system runs steadily and reliably, which fully meets the requirements of 320 kV heavy ion multidisciplinary research facility and physical experiment.