Least oil film thickness and film thickness ratio of point-line meshing gear meshing points are calculated to estimate lubricating state and discriminate if bringing scoring by using Dowson-Higginson formula and according to elastohydrodynamic lubrication theory.Synthesis radius of curvature calculation formula of meshing points is deduced and normal load of unit tooth width of meshing points is determined.Calculation point of least oil slick thickness is determined according to scoring generating position in point-line meshing gear.Amendatory least oil slick thickness calculation formula is brought forward according to a lot of practicable calculation.