Abstract: This paper is concerned with the relationship among fixed angle (α₂ ), crack growth angle (α'), rotating angle (α) and steel angle (α_s ) of reinforced concrete plates. Based on the equilibrium equations, compatibility equations of reinforced concrete plates and the constitutive equations of steel and concrete, a calculation method for the crack growth angle of reinforced concrete plates is proposed. The reliability of the method is verified by comparing the calculation results with the test results of the two plates.