Abstract: With the advancement of industrial automation,traditional PLC data processing methods are facing challenges in efficiency and compatibility. This paper presents a method for converting PLC data to JSON format using the Node-RED platform,which simplifies data processing workflows and enhances data interoperability to support the data integration needs of industrial IoT and smart factories. The limitations of traditional PLC data processing are analyzed，the construction process and configuration steps of the Node-RED platform，as well as the application of the OPC protocol in data collection are described. Through case study analysis，the practicality and efficiency of the proposed method are demonstrated，offering a new technological approach to optimize PLC data processing.

Key words: PLC, Node-RED, JSON, data conversion, industrial IoT