Abstract: The elastic buckling of tapered web plate under pure shear is studied with finite element analysis using the rectangular plate model with inclined stiffeners. Based on the formulas of the shear buckling coefficient for rectangular plate, this paper derives formulas of the shear buckling coefficient for tapered web plates. Two constrain conditions are considered: simply supported of four edges, and simply supported of two opposite edges and fixed of others, by introducing the parameters which consider the influence of tapering ratio. The results of the proposed formulas are compared with those from the finite element analysis. Taking the ratio of free torsional rigidity of the flanges to bending rigidity of the web as a no-ndimensional parameter, the formula of the shear buckling coefficient for tapered web plates is obtained, which could account for elastic restraints provided by the flanges.