In order to monitor the early wearing fault of the metal belt of the vehicle continuously variable transmission(CVT),accurately diagnose the corresponding failure status,the oil condition monitoring system of CVT was designed.By using the selection of fluorescent carbon quantum point to the iron and nickel wear elements in the CVT oil,the fluorescence intensity quenching rate of carbon quantum dots was calculated,and the ratio of iron and nickel elements in the transmission oil under different driving mileage was analyzed.By comparing the metal element content of the materials of the metal parts of the transmission,it is found that the the main fault location is at the steel ring of CVT when driving to 30 000 km.The validity and rationality of the experimental results is verified by combining the oil spectrum analysis technology and immune principle.Through the analysis of transmission disassembly and inspection,the accuracy of the experimental method is further verified,and the practical feasibility of CVT oil condition monitoring system is proved,which provides a new method for early failure diagnosis of transmission.