The crack closure phenomenon is important in the aspect of effecitve driving force for crack growth. Therefore, the precise measurement of crack closure load is an essential prerequisite for the determination of the effective driving force. In this study, the acoustic emission(AE) technique was employed as one of crack closure measurement methods and the results were compared with those of crack opening displacement method(CD), back face strain gage method(BFS) and surface strain gage method. Results have shown that the intrinsic fatigue Life curve(da/dN vs. ΔK_(eff)) obtained by use of the AE technique vvas best fit with the curve of high stress ratio (R=0.8) test, which implied that the AE technique could be considered as a reliable crack closure measurement method.