Abstract: The experiment of reinforced concrete (RC) beams under a combined action of shear and bending indicated that there is a Moment-Shear correlation. The capacity of RC shear-bending components is calculated separately according to the methods of pure shear and bending in GB50010-2002, which will cause low reliability and the demand of GB50068-2001 cannot be satisfied through analysis of existing test data, a modified formula based on 1/4 arc and its calculation method is proposed. The correlation of shear and bending actions is considered in this formula, which have a definite physical meaning. Results show that the computing model of the modified formula is more accurate and its reliability can meet approximately the demand of GB50068-2001.