The invention relates to a high-precision ultrasonic double-sheet detector. The instrument includes a processor circuit, a display circuit, an execution circuit, a signal processing circuit, a receiving circuit, a power supply circuit, a transmitting circuit, a temperature compensation circuit and a keyboard circuit. The present invention can monitor the paper feeding situation of the printing machine in real time, and output four states of empty sheet, single sheet, double sheet and alarm according to the propagation speed and energy loss of ultrasonic waves in the paper and air, so as to control the action of the paper feeding mechanism. A device, the system increases the temperature compensation circuit and software filtering method to improve the detection accuracy. The instrument has the characteristics of low cost, high speed, high precision, easy installation, etc., and can be used as a general double sheet detector.