Abstract: In view of problem that existing coal automation control system has many different communication protocols, data conversion and data integration are difficult, an OPC server based on ASOPCDA.DLL was developed, and its development flowchart and application in coal preparation plant were introduced. The server can convert different communication protocols into a universal OPC communication protocol, and it will be convenient for the data integration to the device by upper layer software, which provides communication protocol basic support for informatization.