In this paper the mechanical analysis of the film picking forks roller tooth in field -cleaning machine was done. A finite element analysis model was built and used by the non-linear finite element analysis method. It is obtained from the result of post-processing calculation and analysis that according to the Fourth Strength Theory, the maximum equivalent stress on the pole tooth root under the uniform load. Root strength should be strengthened to ensure the evenly stress overall the pole tooth, because pole tooth root department would be deformed easily. And the largest stress is at the end of pole tooth and decreases gradually from end to root, and deformation is also the same. Based on the analysis of strength and rigidity, the bearing forces and deformation of the film picking forks roller tooth in work were predicted and validated. It was found that the finite element analysis and the result of test were well coincided. The reliable tool was provided for the design of the film picking forks roller tooth by the finite element analysis. The Roller tooth was designed and improved according to the requirement of deformation and operation.