To address the problems of seed bouncing and non-uniform distribution during the seed delivery process of wide belt seed wheat planters, a pneumatic wide belt seed delivery device based on the action of a slit-induced adsorption force field was designed. A slit structure was introduced into the device to generate a localized adsorption force field, enabling uniform division of the falling seed population. Discrete element and finite element methods were employed to model and optimize key parameters, including the slit structure and the length of the intermediate section, thereby clarifying the effects of structural parameters on seed-guiding behavior and the uniformity of the pneumatic action zone. The pneumatic seed delivery process was simulated using a CFD-DEM coupling method. Air pressure, seeding rate, intermediate seed-guiding channel width, and slit structure were selected as influencing factors, while the longitudinal seeding rate consistency coefficient of variation among rows and the transverse in-row coefficient of variation were used as evaluation indices. Regression models were established using Minitab, and response surface analysis was conducted to determine the optimal parameter combination. The results indicate that seeding rate, slit structure, and intermediate seed-guiding channel width have significant effects on the coefficient of variation of longitudinal seeding rate consistency among rows, whereas seeding rate, air pressure, and channel width significantly affect the in-row transverse coefficient of variation. When the air pressure was -0.8kPa, the seeding rate was 150kg·hm-2, the seed-guiding channel width was 11mm, and the slit structure was rectangular, both coefficients of variation reached their lowest overall levels, with the longitudinal seeding rate consistency coefficient of variation at 2.16% and the in-row transverse coefficient of variation at 8.97%. Bench tests further verified the simulation results. With increasing positive pressure, the coefficient of variation of seeding rate consistency among rows first decreased and then increased under low seeding rates, while it continuously decreased under high seeding rates;a backflow phenomenon occurred when the air pressure reached approximately 2.25kPa. The in-row transverse coefficient of variation remained generally within the range of 8%~15% with no significant variation, meeting the operational requirements for precision and uniform wheat sowing.