A rotor jumping detector designed by the invention comprises an ARM core board, and is characterized in that the front end of the ARM core board is provided with a 4-channel 16-bit analog-to-digital conversion circuit and a sampling control logic circuit, wherein the sampling control logic circuit is in data connection with the 4-channel 16-bit analog-to-digital conversion circuit, and a sensor signal processing circuit is arranged in front of the 4-channel 16-bit analog-to-digital conversion circuit and the sampling control logic circuit. According to the rotor jumping detector, the synchronous data collection to the signals of a rotor mechanical jumping sensor and a comprehensive jumping sensor is completed by the ARM core board, corresponding mechanical jumping data, comprehensive jumping data and electric jumping data are obtained by processing the data and computing and displayed on a liquid crystal display; meanwhile the test data is uploaded to a superior monitoring computer for further analysis, and provided to a user in the manners of jumping data circumferential oscillogram, polar diagram and the like, and then the user can check the processing quality of the rotor.