The Combined Studded Feed Roller Seed Metering Device is a new metering device used for sowing in lines of no-tillage planter, which has many advantages such as good universality and convenient adjustment of application rate, and hign precision of sowing minimum–seeding especially for the small seeds (such as Alfalfa,Millet and Rapeseed ) .

In this paper,the size of big studded feed roller nail tooth gap of the combined studded feed roller seed Metering device had been analyzed in theory from the structure and the work principle,which combining the size of crop seeds,provided theoretical direction for the further study and optimum structure on the combined studded feed roller seed metering device of no-tillage drill for the future.