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Aiming at the problems of poor mobility caused by uneven surface and irregular shape of seeds, poor seed filling performance caused by population compaction and axial dispersion of three seeds per hole, a combined hole filled seed metering device was designed. The length of the outer hole of the inner socket was designed to improve the filling performance. Based on the principle of the brachistochrone, the surface of the backflow plate was designed, and the range of the upper end inclination of the backflow plate, the placement position and the movement of the seed on the backflow plate were theoretically analyzed. The collision process between seed and forced seed metering mechanism was analyzed, and the gathering seed metering mechanism was designed and optimized. The population backflow movement process and gathering seeding process were analyzed by EDEM simulation, and the population movement mechanism with backflow plate was proved. It was concluded that the backflow effect of backflow plate with an inclination of 32° was better, indicating that the backflow plate could enhance population mobility and avoid population accumulation. The analysis proved that the gathering seed metering mechanism can improve the hole collection effect of the seed metering device and achieve the consistency of three seeds. At last, the highspeed photography experiment of seed throwing consistency, single hole test, double factor experiment and acupoint gathering test were carried out. Through high-speed photography, the law of displacement and speed change of Cyperus esculentus seeds was analyzed. The results were basically consistent with the numerical simulation. From the single hole seed metering wheel seed metering experiment, it was found that there was no significant difference in the seed metering qualification rate of three rows of holes. The double factor experiment showed that when the inner hole length of the double hole was 8mm and the rotational speed was 20r/min, the qualified index, missing index and multiples index of the seed metering device can reach 96.4%, 1.5% and 2.1%, respectively. Under the conditions of better inner cavity length and reflux plate, the experiment results showed that the best effect was at speed of 10r/min and 20r/min.