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For solving the problem of turbulence and other phenomena destroying the uniformity of seed flow distribution during the working process of the pneumatic seeding system distributor, a bionic design method of the distributor based on the streamlined curve of crucian as a bionic prototype was proposed. The crucian was three-dimensionally scanned to obtain point cloud data, and four crucian streamline curves were fitted by Matlab, and four different structural distributors were designed by the curves. At the same time, the standard k-ε model unsteady Lagrangian coupling algorithm was used to simulate the four types of bionics. The gas-solid coupling simulation comparison between the structure distributor and the original structure distributor was carried out to obtain the optimal structure. The quadratic regression universal rotating combination design test was adopted, the seeding rate and the fan frequency were used as influencing factors, and the coefficient of variation of the discharge consistency of each row was used as the test index to carry out the verification test for the optimal structure distributor. The simulation analysis results showed that the distributor designed by the upper curve of the front basically eliminated turbulence and had the smallest coefficient of variation between the pressure loss and the displacement of each row. It was determined that it was the optimal structure. The verification test results showed that the maximum value of the coefficient of variation of the consistency of each row of the optimized distributor was 3.72%, which was less than the standard requirement and met the actual production demand, indicating that the streamlined distributor can effectively improve the uniformity of seed distribution in the seeding system. It can provide reference for the design and optimization of the distributor for the air conveying type metering system.