Abstract: To timely inform the combine harvester feed rate when the combine harvester was harvesting in field, the core components of tangential drum, the assisting feeding drum and longitudinal-axial drum taken from the tangential-axial combine harvester were used to build tangential-longitudinal-axial threshing-separating test-bed in the laboratory. The performance experiments of wheat threshed and separated with the feed rate of 1-8 kg/s were executed on the tangential-longitudinal-axial threshing-separating test-bed. The power consumption of the tangential drum, the power consumption of the assisting feeding drum and the power consumption of longitudinal-axial drum were measured on the test-bed. Mathematical formulas between the feed rate and longitudinal-axial drum power consumption were derived based on analysis the wheat threshed and separated power on the tangential-longitudinal-axial threshing-separating test-bed. The predicted feed rate of wheat was verified by executed the randomly feed rate experiment on the tangential-longitudinal-axial threshing-separating test-bed. The results showed that the wheat feed rate of the test-bed was accurately predicted by the derived mathematical formula. When the wheat feed rate was less than 6 kg/s, the prediction error was less than 0.89%. When the wheat feed rate was 7-8 kg/s, the prediction error was 1.02-1.42%.