The Allium chinense, a perennial plant of the Allium genus in the lily family, is predominantly found in the Yangtze River basin and southern regions of China, with a cultivation area exceeding 6.6×104hm2. It boasts a unique flavor and high medicinal and edible value, being extensively exported to countries such as Japan and South Korea. It has become a characteristic industry and foreign exchange product for implementing the “Rural Revitalization” strategy in some areas, with broad market prospects. Currently, the cultivation of Allium chinense largely relies on manual labor, which is physically demanding and costly, thus hindering the industry’s large-scale development. There is an urgent need to develop and apply mechanized planting equipment for Allium chinense. Aiming to address the agronomic specifications regarding the orientation of bud scales and the engineering requirements for low-position discharging during the mechanized planting of Allium chinense, a flexible belt clamp directional discharging device for Allium chinense, based on the spoon clip type seed metering device was engineered. The mechanism comprised a feed deflector, conveyor systems, electric motors, synchronous pulleys, and flexible belts, among other components. The operational principle of the flexible belt clamp seed discharging device was subjected to theoretical analysis, with a focus on the feeding, seed posture correction, and seed discharging processes. This analysis facilitated the determination of the structural design and parametric specifications for critical components. A coupled simulation model was constructed, integrating multi-flexible body dynamics (MFBD) and the discrete element method (DEM). Using response such as the seed horizontal discharging rate, horizontal seeding rate, and qualified rate of hole distance, a significance screening of the coupled simulation experiments was performed, considering five key factors: the clamp belt angle, theoretical conveying speed, belt speed differential ratio, clamp belt spacing, and feeding radius. Subsequently, a regression orthogonal field test was executed, focusing on the clamp belt angle, theoretical conveying speed, belt speed differential ratio as experimental variables. Employing the Plackett-Burman design and the Box-Behnken central composite design, regression models were formulated for the seed horizontal discharging rate and the qualified rate of hole distance. These models were then utilized for parameter optimization, yielding an optimal parameter set: a clamp belt angle of 65°, a theoretical conveying speed of 0.38m/s, and a belt speed difference ratio of 1.64. Field test were conducted under the optimized parameters, and the findings indicated that at a forward speed of 0.16m/s, the average seed horizontal discharging rate and the average qualified rate of hole distance achieved by the device were 61.11% and 78.89%, respectively. The experimental results demonstrated deficits of 4.17 and 1.15 percentage points relative to the model-predicted optima. The outcomes of this research can offer valuable insights for the development and design of mechanized orientation seed planting equipment for Allium chinense.