In the rail transit industry, the electric locomotive’s electric motor is used as the driving core, and its installation and working environment are often harsh, and the probability of failure will increase accordingly. If the motor fails during the operation of the locomotive, it will cause huge economic losses, and even threaten people’s lives and property. In order to grasp the running status of the motor in real time, an online monitoring system of the motor status is designed. This system collects the three parameters of temperature, current and speed, and inputs the three-parameter data into the single-chip microcomputer. The single-chip microcomputer transmits the data to the host computer through calculation. The host computer analyzes and displays the data through LabVIEW to realize online monitoring of the motor status. Experiments show that the system has a good man-machine interface, a wide speed range, high accuracy, fast response speed, and strong anti-interference ability, which is of great practical value for online monitoring of motors.