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A type of anti-blocking mechanism, used on no-till precision planter for wheat stubble fields, was designed. The purpose was to solve straw burning and residue blocking between seeding units which were caused by large amount of straws and higher stubbles in annual double cropping area of Huanghuaihai. In order to find out reasonable structure and operation parameters of the anti blocking mechanism, optimization experiment was conducted with orthogonal test method of three factors and three levels. The optimal parameters combination was as follows: the operation speed of 4.5km/h, the arrangement of blade of 4-3-4, the rotating speed of blade shaft of 400r/min. The field experiment result showed that when the cutting depth of blade was 20~30mm, the soil disturbance was 63%~76%, the anti-blocking mechanism could solve the problem of straw blocking and improve the seeding quality. 