Two parameter fracture criterion is a simple method to predict residual strength. However, some assumptions were taken by the initial derivation process. To provide a more rigorous deduction, two parameter fracture criterion was derived strictly based on Neuber equation. Besides, two parameter fracture criterion was simplified by replacing specimens’ critical crack lengths with initial crack sizes. The residual strengths of M(T) and C(T) were predicted by this simplified method, and the estimated errors are less than 7%. In order to verify the capability of this simplified method to predict the residual strength of complex structures, the residual strengths of three-hole crack tension specimens were predicted, and all of these discrepancies are less than 5%.