The OPC UA standard overcomes many disadvantages of the traditional OPC, and has significant advantages in platform independence, communication security and model construction, thus completing the information exchange under different platforms and interfaces. At present, the automation system equipment has the problems of complex protocols and interfaces and poor portability of industrial computer. To solve this problem, this paper develops the ARM embedded OPC UA client to complete the data communication with the automation system device server by porting the open62541 open source library on the ARM embedded device equipped with the FreeRTOS system. In this research, by building the OPC UA client on the embedded system, the connection and communication with the server are realized, which is also cheap and flexible to use. Experiments show that the system can be used in equipment debugging, field operation and emergency control, and has a wide range of application prospects and practical value.