On the basis of available testing data of simply supported reinforced concrete beams without web reinforcement under two-point concentrated loads,the dominant factors contributing to shear performance are identified,and the basic laws are correspondingly quantitatively described.The shear design equations of China Design Code of Reinforced Concrete Structures,ACI Code,together with two other expressions of shear of RC beams without web reinforcement,are thus calibrated to identify their accuracy in describing the shear mechanism of such members.