Abstract: Based on the assumptions that a plane section before bending remains a plane after bending and no relative movement takes place between steel and concrete, an expression for the flexural rigidity of steel reinforced concrete (SRC) beams as a function of the rigidities of steel and concrete was derived. The approximate and simplified formulas for calculating the flexural rigidity of SRC beams were proposed based on the expression, the relevant formulas given in the Chinese current design codes for concrete structures, the approximate position of neutral axis and the approximate stress factor of the reinforcement including the tensile flange of steel. The proposed formulas agree well with experimental results and may be used as a reference for structural engineers.