Abstract: In this paper,the equivalent yielding stress and equivalent strain hardening exponent are systematically calculated of welded center cracked specimen with the fully plastic finite element method.The formulas for estimaing equivalent parameters given are very convenient for engineering.An universal estimating procedure for fracture mechanics parameters compatible to EPRI approach is obtained,and it can be used for both homogenious material and heterogeneious material,making the EPRI engineering approach a new step.