The bolt made of GFRP, which guarantees the properties such as sufficient electric insulation, is utilized as one of joints. It is important for the design of joint to check the stress distribution of bolt thread and to evaluate the fatigue characteristics. The purpose of this study is to evaluate fatigue characteristics of GFRP bolt by an analysis considered with anisotropic properties of failure modes. In particular, the results of FEM analysis have been reflected the failure modes of fatigue tests. The stress distributions along the bolt thread made by GFRP differ from traditional those. It is revealed that the differences of the stress and the strength cause the complex failure modes.