On the basis of the study of contact mechanics and kinematics of precision steel ball transmission,the minimum film thickness formula of precision steel ball transmission meshing vice is derived by applying Hamrock-Dowson formula.The influence rule of the basic parameters such as the short amplitude coefficient of cycloidal tooth profile,rolling circle radius and steel ball radius on the meshing pair minimum film thickness is studied by applying numerical calculation method.The lubrication condition of meshing pair is analyzed and discriminated,the calculation method of the parameter selection of meshing pair in a state of complete elastohydrodynamic lubrication is proposed with calculating the range of the basic parameters.The theory basis of design and application for precision steel ball transmission is provided.