In order to analyze the working performance of the rethreshing separation unit combined with a tangential-threshing and an axial threshing, including losing rate, distribution of the mixture along the axial of cylinder, the rate of impurity and power consumption, three threshing drums, i.e., the spike tooth, the rectangular tooth or the spike-short-rasp-bar tooth, were developed and test on the rig of the axial-threshing separation performance with axial feeding. The results show that three drums have low losing rate. Compared with the spike tooth and the rectangular tooth, the drum with spike tooth and short-rasp-bar tooth has uniformal distribution of the mixture along the axial of cylinder, less impurity contents and lower power consumption while threshing wheat.