Based on the status of the gear box widely used in machinery and equipment, to meet the demand of enterprises for its operational status evaluation of reality, the study design platform system is carried out for gear box monitoring and diagnosis,multiple indicators such as temperature, vibration, realtime display the running status of gear box and the expert system to diagnose the abnormal data feedback. The system was developed based on the J2EE platform and SSH threetier architecture. MySQL was invoked at the bottom and ECharts was used at the interface layer to operate on the data. With Jess engine as the core reasoning module, an expert system based on isolated forest and fuzzy reasoning was established. The system shows the operation data of gearbox in real time, and accurately completes the diagnosis and feedback of abnormal data, which can be used effectively in the field of real industry.