A forced opening mechanism on the peanut dibbler had been designed to solve the problems that the duckbills in the model of 2BHM–2 peanut planter couldn’t open timely or the membrane damage caused by pressure plate. The forced opening mechanism was consisted of moving duckbill, fixed duckbill, stir bar, and limit block. When working, the active duckbill could be opened and closed with fixed duck’s mouth under the drive of the pole and the limit block, to complete the spaced sowing. The structure parameters of the opening mechanism were determined by the analysis of the rolling state diagram of dibbler and the agronomic requirements. The width and the height of duckbill were 30 mm and 50 mm. The length of stir bar was 89.7 mm, and the short arm was 37.6 mm. The limit block was 119.4 mm from the center of the wheel disk. A field experiment was conducted for comparison between the model and the original opening clamp mechanism. It was obvious that the original pressure plate type was restricted by soil conditions, and the lowest pass rate was 85%, whereas it can reach above 90% for the forced opening mechanism with an increase of 5.8%. The damage degree of the film for the original pressure plate type was higher, but was basically zero for the forced opening mechanism.