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For improving the pressing quality of seed belt made by the pressing rollers of the precision sowing apparatus, the influences affected by the change of the deflection of rollers on the pressing force were researched. And then, the change of the deflection was compensated with the method of setting crown, while the valve of the crown was solved by the theoretical calculation. After that, the optimum pressing force was measured in the test, and the range of which is from 45N to 160N. So, the force inflicted on the two sides of the roller was calculated as 3405N. Then, with the difference and iterative calculation, the valve of the crown was set to 0.35mm. In the final, the force valves of the certain points along the rollers were tested in the experiment. The results showed that the valves and the distribution of the forces between the two rollers were basically same as theoretical analysis, and the effect of seed belt was good enough to pave in the woodland.