Abstract: According to the method of seed harvest and agricultural technical requirements of wheat breeding experiment， a wheat breeding combine harvester was developed through theoretical analysis and field experiment. The machine could complete cutting， threshing， separating， cleaning， collecting grain in one time. Operating performance test was conducted with feed quantity， rotate speed of cylinder， rotate speed of gettering fan as testing factors， and the threshing total loss rate， threshing broken rate and trash content of cleaning rate as evaluating indicators. Comprehensive balance method and orthogonal experiments were applied to obtain the optimum scheme of the whole parameters when operating， in which the feed quantity was 0.3 kg·s-1， the rotate speed of cylinder was 1 350 r·min-1 and the rotate speed of gettering fan was 1 000 r·min-1. Field test with the optimum combination of operational parameters showed that the average threshing total loss rate was 0.43%， the average trash content of cleaning rate was 15.03%， the average threshing broken rate was 0.48%， and the remaining rate of seed was 0， which could meet the demand of plot wheat breeding harvest.

Key words: agricultural machinery, plot breeding, combine harvester