Abstract:Aiming at the problems that multiple floating debris like sand and broken straw are often sucked into seeding compartments by airsuction seedmetering devices during notillage sowing operations, causing lower seed metering quality, a flexible mechanical type soybean seedmetering device with seedcleaning and maintaining functions was designed. Through a series of theoretical analyses of operation process of seedmetering device, the main structures and working parameters which might affect actual working performances were further determined. And by selecting PE wire, bristle and nylon as seedprotecting brush materials, a series of singlefactor comparisons were conducted, it was showed that there was no significant difference between bristle and nylon in making effects on pass indexes. But PE wire had significant effects upon these pass indexes. As for effects on missedsowing index and repeatedsowing index, there was no significant difference between nylon and bristle. However, PE wire achieved significant effect upon this index. For the damage index, there were significant differences between the above three materials. And through further comparative analyses, by selecting nylon as brush material, adopting 3factor 5level orthogonal revolving combination way and Design-Expert 8.0.6.1, taking operation speed, seedfilling inclination angle and seedprotection distance as test factors, as well as applying pass index, missed index, repeated index and damage index as evaluation indicators, the experimental data was further processed. It was showed that the actual effect degrees of all the above factors which made on pass index were operation speed, seedprotection distance and seedfilling inclination angle from the greatest to the least. Actual effects of all the above factors made on index missedsowing index were seedprotection distance, seedfilling inclination angle and operation speed from the greatest to the least. And actual effects of all these factors made upon repeatedsowing index were operation speed, seedfilling inclination angle and seedprotection distance from the greatest to the least. And actual effects of all these above factors brought on damage index were seedprotection distance, operation speed and seedfilling inclination angle from the greatest to the least. When operating speed was 8~12km/h, seedfilling inclination angle reached 70° and seed protection distance came to be -1.5mm, such seedmetering device can pass 94% of total seeds, and missedseeding index was less than 3%, missedsowing index was less than 3%, and damage index was less than 0.2%, meeting the agronomic technical requirements for soybeans highspeed precision sowing under condition of notillage.