Abstract: The seed movement as a whole in the vertical cylinder seed chamber of clamping dibbler wheel has important effects on precision seeding of the dibbler wheel. The purpose of this work was to disclose the law of seed movement in the seed chamber by methods of mechanical analysis and experiment. Seeds as a whole in the seed chamber are forced by two torques relative to the centre point of the seed chamber, which are clockwise and anticlockwise torques, when dibbler wheel rotates. The clockwise torque makes the seed population to slip down on the inner side of the chamber, and the anticlockwise torque makes the seed population to rise and do circular motion around the centre point of seed chamber. When values of the two torques are equal, the depth of seed in the seed chamber is called seed slipping critical depth. Given that seed depth in the seed chamber is lower than seed slipping critical depth, seeds will slip on the inner side of the seed chamber as a whole; otherwise, seeds will go up along the inner side of seed chamber. The experiment showed that the seed critical depth was 0.05 m when seeding devices were not equipped in seed chamber, and the seed critical depth was 0.01 m when seeding devices were equipped.