A vehicle-mounted device and a fleet management system are disclosed. The vehicle-mounted device is mounted in a vehicle equipped with an OBD module that provides vehicle status parameters, including a sensor module mounted in the vehicle, a sensor module mounted in the vehicle and used to detect the real-time driving status image and driver status image of the vehicle, a general control module electrically connecting the sensor module and the OBD module for receiving the vehicle status parameters of the OBD module and the real-time driving status image and driver status image of the vehicle, and a judgment module electrically connected to the general control module to judge whether the driving of the vehicle complies with the driving specifications according to the data received by the general control module.