For analyzing the threshing and separating performance of tangential flow threshing and separating unit of axial flow combine, the threshing, separating and cleaning test-bed of axial flow was developed. Spike tooth and knife tooth were applied to the tangential flow threshing and separating unit. The power consumption of tangential flow threshing cylinder, force-feeding drum and axial flow cylinder were experimentally measured. The effects of structure and motion parameters of tangential flow threshing and separating unit on threshing performance were studied. The experimental results showed that threshing rate of tangential flow threshing and separating unit was in the range of about 67.19%–82.37%, and its power consumption accounted for about 20% of total threshing power consumption, the power consumption of tangential flow unit using knife tooth was lower than that using spike tooth, the threshing rate of tangential-axial flow threshing and separating test-bed was higher than 99.90%, the entrainment loss ratio was less than 0.25% for wheat harvest. The power consumption of tangential-axial flow threshing and separating unit using tangential flow threshing cylinder of knife tooth was lower than that using tangential flow threshing cylinder of spike tooth. The force-feeding drum and axial flow threshing cylinder accounted for about 14% and 66% of total threshing power consumption, respectively. The results provide guidance for the development of axial flow combine.