Abstract: An experimental and computational study of EN-31 steel Compact Tension specimen was performed. Compact Tension specimen was considered in the experimental portion of the study. Stress intensity factor, Crack tip opening displacement (CTOD) & J integral were main parameter found by the experimental analysis. Load vs CMOD graph are used to get the important parameter. The same parameters also investigated by the Finite element method for CT specimen. A comparison with a Experimental Vs Computational investigation on an EN-31 compact Tension specimen suggests similarities concerning the interaction between material nonlinearity and specimen response nonlinearity.