In order to meet the requirements of precision planting and improve the seeding quality of potato seed metering device, a kind of doublerow cross spoonbelt potato precision seed metering device was designed. The overall structure and working principle of the seed metering device were illustrated and analyzed. The optimal design of structural parameters of key components was conducted, such as the doublerow cross seeding assembly, the driving assembly and the vibration cleaningseed assembly. To improve the working performance of the metering device, obtain the best operation parameters, the quadratic general rotary unitized design was carried out with the rotational speed and the amplitude of seed metering device as the experiment factors and the seeding qualified index, the relaying seed qualified index and the missing seed qualified index as the experimental indexes. Based on experimental data, a mathematical model was built by using the Design-Expert 6.0.10 software, and the experimental factors were optimized, the best combination was achieved. Test results showed that as the rotational speed was 31.5r/min, the amplitude was 11.7mm, and the seeding qualified index was 89.92%, the improved metering device exceeded the original one by 19.9%, the relaying seed qualified index was 5.12%,and the missing seed qualified index was 4.96%. On the basis, the metering adaptability filed 〖JP3〗test was carried out, and then test results showed that the seeding performance of seed metering device to all size grades of potato seeds could meet the requirements of precision planting. The results can provide the guidance and direction for the research of potato precision seeder and its key parts.