The invention relates to a vehicle-mounted monitoring device for an urban rail vehicle. The vehicle-mounted monitoring device comprises a train automatic control interface and a power supply module, and further comprises a CPU (Central Processing Unit); the CPU is connected with the train automatic control interface, and is further connected with an SD (Secure Digital) card and a clock unit; and the power supply module respectively supplies power to the CPU, the CD card and the clock unit. The vehicle-mounted monitoring device provided by the invention has the beneficial effects of large data collecting amount and overall information. With the adoption of the vehicle-mounted monitoring device, information is conveniently extracted (only by taking out the SD card and obtaining relevant operation information according to files corresponding to a date and time in the SD card), so that not only the fault analyzing time is greatly reduced, and the fault processing accuracy is improved, but also the maintenance efficiency can be improved, and the quantity of trip riders is reduced. Therefore, the maintenance cost is saved.