Three-link reducers are widely used in petrochemical, mining and other fields for their high transmission ratio, high capacity and high transmission efficiency. Tooth racks are the key components of a three-link gear-reducer. In this paper, in order to obtain the fairly accurate link board stress distribution, we use the PRO/E software to establish the 3D models, carry out theoretical analysis of the link board overall stress and analyze the stress of the tooth rack with ANSYS software. Three-link reducers are widely used in petrochemical, mining and other fields for their high transmission ratio, high capacity and high transmission efficiency. Tooth racks are the key components of a three-link gear-reducer. In this paper, in order to obtain the normal accurate link board stress distribution, we use the PRO / E software to establish the 3D models, carry out theoretical analysis of the link board overall stress and analyze the stress of the tooth rack with ANSYS software.