Aiming at the problems of poor seeding quality and unstable performance of the duck-billed corn seed metering device under slope farming conditions, taking duckbill corn metering device as carrier, an intermittent synchronous seeding and reseeding device was designed. The overall structure and working principle of the seed metering device were described, the seeding, reseeding and seed guiding process of the corn seeds inside the seed metering device were analyzed, the structure parameters of key components such as the intermittent synchronous seeding and reseeding device of rocker, inner ratchet and duckbill type seed metering device of right-angle seed guide components were optimized. Combining theoretical analysis and agronomic requirements for sloping farmland sowing, the single factor test, orthogonal test and bed comparison experiment were carried out by selecting operating speed, return spring preload and operating slope angle as test factors, and taking seeding qualified index and seeding coefficient of variation as test indicators. The experiment results showed that the performance index was increased first and then decreased with the increase of working speed and working slope angle, as the return spring preload increased, it was firstly increased and then stabilized. When the operating speed was 1m/s, the return spring preload was 15.6N (model T4, wire diameter was 1mm, middle diameter was 7mm, original length was 25mm), and the operating slope angle was 12°, the seeding performance was the best, with seeding qualified index of 98.7% and seeding coefficient of variation of 10.2%. Compared with the traditional duckbill precision seed metering device, its eligibility index was increased by 9.5 percentage points, and it can meet the requirements of planting operations in sloping farmland environment. The research result can provide reference for the R&D and design of key technologies and supporting working parts for seeding under sloping farmland conditions.