Abstract: Two approches predicting fatigue crack initiation life that the notch size into account are presented in this paper. The first approach considers size effect in terms of high strain area volume near notches and establishes an empirical fomula using W versus Ni data. In the second approach fatique notch factor Kf is substituted for theoritical stress concentration factor Kt to take the size effect into account and J modified with Kt is used to replace J to obtain life pre dieting formula. The accuracy of the first approach is found higher, but the second approach is simpler.An approach to determine fatique notch factor Kf using fracture mechanics method is also given in this paper. Finally it is pointed out that the prediction of fatique crack initiation life by notch cyclic J integral is closer to the test results than that by notch tip's maximum deformation work range derived from Neuber formula.