In order to adapt simplification precision hilldrop seeding for conventional rice and simplify the seedmetering device, a unique Ushaped cavity type precision hilldrop seedmetering device for rice was designed. Based on the mechanical characteristics of rice seeds and its agronomy requirements of hilldrop seeding, a cavity type seeding plate was put forward, which characterized with seeddropping orifice and seedfilling orifice connected by the cavity, the mechanical models of the process of seed filling and dropping were constructed, and the main structural parameters of the seeding plate were determined. The seeding objects was “Huanghuazhan” (conventional rice), experimental studies were respectively carried out on the effects of the number, length, width and inclination of the seedfilling orifice and seeddropping angle on the seeding performance of precision and hilldrop of the seedmetering device by means of highspeed camera and JPS-12 type seedmetering device performance test bench. Highspeed camera test results indicated that the precision seeding performance of the seedmetering device was better when the number, length, width and inclination of the seedfilling orifice were 20, 10.6mm, 7.6mm and 0 degree, respectively. Correspondingly, the missseeding rate (less than 3 seeds per hole), qualified rate (3~8 seeds per hole), reseeding rate (more than 8 seeds per hole) and seed damage rate were 0.40%, 94.00%, 5.60% and 0.13%, respectively. JPS-12 type seedmetering device performance bench test results indicated that the seeddropping angle very significantly affected the average value and qualified rate of hole diameter, and significantly affected the variation coefficient of hole distance. The suitable seeddropping angle of seedmetering device was 28°~33°. Under the above range of seeddropping angle, all the average hole diameter were not more than 27.14mm, all the qualified rate of hole diameter were not less than 96.67%, all the average hole distances were about 140mm, and all the variation coefficient of hole distance were not more than 7.80%. The results of field experiment showed that the qualified rate, missseeding rate and reseeding rate were 90.28%, 0.83% and 8.89%, respectively. And the average hole diameter of 46.71mm, qualified rate of hole diameter of 71.67%, average hole distance of 137.21mm and variation coefficient of hole distance of 12.64% were found in the field experiment. All the sowing performance satisfied the general precision direct hilldrop seeding requirement of conventional rice in field. The research result provided a theoretical reference for the simplification design of the mechanical seedmetering device.