One of the important subjects in fracture mechanics study is to analyze the stress intensity factor. In this paper, the stress intensity factor in Mode I ($K^{I}$) is determined by J-integral using the finite element method. In this investigation, the values of $K^{I}$ are computed for distorted and undistorted elements of 8-noded isoparametric finite elements. The numerical results obtained are summarized as follows. (1) Through a relatively coarse mesh, the $K^{I}$ values obtained by this method are fairly good accuracy. (2) The $K^{I}$ values for the distorted elements appear to be better than those obtained using the undistorted mesh. (3) Within the limits of these analyses, the solutions obtained through the integral paths in the medium region of elements approach to the analytical solution most closely.