The current engineering fracture criteria K_c , Φ_c and ω _c ⁺ for brittle fracture initiation are critically reviewed analytically and experimentally. The followings are obtained conclusively : (1) The fracture initiation in existence of residual stress, say due to welding performance, pre-loading etc., is explained equally well by Φ_c or ω _c ⁺ criterion, but not by K_c criterion. (2) Φ_c criterion is refered to qualifying examination as a fracture criterion throughout the small & large scale yielding regions. It is confirmed that COD test on small specimen can predict the fracture behaviour of large specimen or structural member. (3) The value of Φ_c is dependent on degree of triaxiality of stress or plastic constraint (notch acuity, plate thickness, structural constraint etc.) as well as temperature.