Power measurement is one of the important methods for the detection of feed rate of combine harvester. In order to more accurately analyze the accuracy of the feed rate detection methods at different positions, two feed rate detection methods and devices were designed based on power of header driving shaft and power of tilting conveyor. Winter wheat in Hebei Province was used as the test object, and Xinjiang-3 harvester was used as a test platform and a system test was performed. The feeding amount detection system included a header active shaft torque sensor, a tilting conveyor power shaft torque sensor, a header active shaft speed sensor, and an on-board industrial computer. Through field experiments, two feed rate detection methods were analyzed and compared, and the calculation models were established based on the test data. The test results showed that the relative error of the method based on the power of driving shaft of cutting table was 19.6%, and the relative error of the method based on power of tilting conveyor was 16.1%. The detection accuracy of both methods can meet the needs of field application to a certain extent. The detection accuracy of feed quantity based on power of inclined conveyor was slightly higher than that based on power of driving shaft of cutting table.