In order to solve the problem of small seed's precision seeding, such as vegetable and flower seeds, a new type of magnetic cylinder-seeder was developed according to the magnetic seed-metering principle. By analyzing and comparing magnetic field route and intensity of one row suction head in the case of two kinds of polarity arrangements, the designed project was ascertained that four rows of magnetic suction head were assembled in the cylinder inner and its pole was arranged according to gap way. To improve the metering performance of this device, the orthogonal experiment was conducted with test object of rapeseed coated with magnetic powder, test factors of cylinder rotation rate and suction head's electric current. Variance analysis of the experiment results indicates that the suction head's electric current is the main factor and the optimization of two factors are the suction head's electric current of 230mA and the cylinder rotation rate of 15r/min. Under such working conditions, the single seed index is 93.6%, multi-seed index is 2.2%, and the seed-metering efficiency could achieve 3600 rows per hour, so it proves that this machine has higher sowing precision and better adaptability to small seeds.