A mechanism is designed to pull out the cotton stalks for the small-type caterpillar self-propelled pull-out cotton stalk machine. The mechanism is mainly composed of the rotating knife roller, the conveying screw tooth, the compression roller and the cleaning roller. For the complex terrain and different spacing in southern, it can pull out cotton stalks on different lines, clean the soil on the root of cotton, and not easy to pull off the cottons. The single factor and multi-factor orthogonal experiments are carried out on the basic factors of the movement speed of machine, the rotation speed of knife roller and the depth of roller blade into soil to affect the respective rate of the cotton stalks being pulled out and off. The results showed that the cotton stalk pulling out rate is 95.8%, and the pulling off is 9.6% when the depth of roller blade into soil is 15 cm, the rotation speed of knife roller is 415 r/min and the movement speed of machine is 0.8 m/s. It is concluded that the depth of roller blade into soil, the rotation speed of knife roller and the movement speed of machine have a significant effect on the rates of pulling out and off.