Abstract: The traditional calculation method of the maximum span is based on Euler beam theory. This method only considers the bending deformation of the cross section and ignores the effect of shear deformation. Based on the simple support beam model of Timoshenko beam theory, the theoretical formula for the calculation of span considering shear deformation is given in this paper. By this formula, for the tubes of DN200 and below, the difference of maximum span based on Euler beam theory and Timoshenko beam theory is less than 1%. For that above DN200, maximum span based on Timoshenko beam theory is smaller than that based on Euler beam theory, and the difference is larger with the increasing of the outer diameter of the pipe. It is suggested to use the formula based on the Timoshenko beam theory to calculate the maximum span of pipes.