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In order to realize wheat precision seeding under clay-wet soil conditions of rice-wheat rotation area, a pneumatic wheat precision seed casting device was developed that casting wheat to clean seedbeds fast and accurately by pneumatic acceleration. The influence of key structural parameters of outlet chamber diameter, throat distance and convergent chamber diameter on velocity of steady gas flow and inlet negative pressure, as test indicators, were studied by numerical simulation and analysis of Fluent software. Analysis results by Fluent showed that the parameter combination of pneumatic wheat precision seed casting device was as follows: diameter of outlet chamber was 6mm, throat distance was 10mm and convergent chamber diameter was 32mm obtained by single factor test as well as three factors and three levels orthogonal experiment. Under this parameter conditions, the velocity of steady gas flow was 524m/s and inlet negative pressure was 15.966kPa, by simulation. Wheat seed casting performance experiment, based on better parameter combination, by test-bed indicated that wheat seed can be casted into soil at high speed to achieve accurate and stable single seed sowing without damage while working speed was 1.2m/s, casting height was 0.1m and air pressure was 0.5MPa. Moreover, the average vesting velocity was 43.8m/s, average depth was 6.78mm, and the coefficient of variation of vesting velocity and average depth was 8.3% and 5.8%, respectively, which showed the stable performance of pneumatic seed casting.