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In order to obtain the best working parameters combination of spiral bar tooth thresher for maize seed production, parameters such as feed rates, threshing rotation speed of roller, spiral angle of bar tooth and exhaust core mouth clamp pressure were selected as independent variables, which would influence kernel broken rate of maize seed. Subsequently, the Box-Behnken experimental design with four factors and three levels was performed, and the mathematical model was established by using Design-Expert software. Then the effects of various parameters and their interactions were analyzed as well. The results showed that effects order of four parameters on kernel broken rate of maize seed were as follows: spiral angle of bar tooth, threshing rotation speed of roller, feed rates and exhaust core mouth clamp pressure. The optimal working parameters were feed rates of 2.8kg/s, threshing rotation speed of roller of 241r/min, spiral angle of bar tooth of 9°and exhaust core mouth clamp pressure of 40N, then the kernel broken rate of seed production of 0.366% was obtained, which was reduced by 0.084%~0.274% after the parameters optimization.