Abstract: The fatigue tests were conducted for the glass fiber reinforced unsaturated polyester resin(GFRP) unidirectional laminates with 0?, 30?, 45? and 90? ply angles respectively. The characters of mean S-N curves and normalized stress versus life curves were investigated with the fatigue test data, and the relationship of the ply angle and fatigue property was obtained. Then, based on the SEM and macro appearances of fatigue fractures, the fatigue failure mode and fatigue failure mechanism for unidirectional laminates with different ply angles were analyzed. As a result, the different combinations of failure mode, which are corresponded to the different failure control mechanisms, are summarized with respect to ply angles.