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To solve the problem that the traditional power supply methods were difficult to adapt to the needs of modern agricultural sensor networks, an electromagnetic self-powered tractor wheel speed sensor based on printed winding and Halbach array was designed. The device adopted the structural form of an intermediate stator and two rotors on both sides. Based on Faraday’s electromagnetic induction law, the output induced electromotive force of the device was theoretically derived and its influence parameters were determined. By using finite element simulation software, the magnet arrangement, coil turns and air gap which affected the output performance of the device were simulated and analyzed, and the best parameters of stator coil shape and permanent magnets pole number were determined. The back-end circuit was designed, which can rectify, measure and transmit the output voltage of the device, so as to calculate the speed, and can be directly supplied by the device. The prototype of the device was made, and the bench calibration test and actual vehicle application test were carried out respectively. The results showed that the linear fitting results of the device speed and voltage were good, the R2 was 0.99991, and the rectified DC voltage at 400r/min was about 3.16V, which can meet the demand of supplying power to the back-end circuit. Compared with the commercial encoder, the measurement accuracy of the speed in the bench test was kept within 1%, and the accuracy in the actual vehicle test was basically kept within 5%. It can meet the requirements of actual use.