It is pointed out that the Tri-linear Model in Concrete Structure Design Code GB 50010-2010 for calculating the bearing capacity of reinforced concrete members under the combined action of shear and torsion enlarges the 1/4 Circular Arc Model and leads to an unsafe design. The formula proposed by Ding Dajun using the 1/4 Circular Arc Model understates the bearing capacity of concrete in choosing the reduction factor of concrete shear capacity. The formula proposed by Huang Liang using the Linear Model makes the design conservative. On the basis of the 1/4 Circular Arc Model, two modified formulas were provided. Practical examples show that Formula 1 and Formula 2 are more secure than the Code formula. Numerical examples show that Formula 1 and Formula 2 not only totally conform to the 1/4 Circular Arc Model , but also approximately conform to the Linear proposed by Huang Liang, and their calculation results are quite similar.