Abstract: Based on the formula of the crack width in the present code,the nominal tensile stress value corresponding to the limit of crack width was studied. The influences of cross section height,the cover thickness,concrete strength grade,non-prestressed reinforcement ratio,diameters of non-prestressed reinforcement and prestress degree on the normal tensile stress of the given crack width were also discussed. Then the influence coefficients of these parameters on the normal tensile stress values were concluded. The comprehensive influence coefficient on the normal tensile stress was obtained by multiplication of the single influence coefficient of the parmeters. In the end,an example was calculated by using the method of normal tensile stress and the formula of the code. The result shows that the method of normal tensile stress is a simple,convenient and creditable method on the crack control of the prestressed concrete structures.