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Joints represent potential weak points in the structure, the design of the overall structure tends to follow from the design of the joint. To date, metal/composite joints are general in current aircraft structure. Some of the reasons for lower joint efficiency in composites are: brittleness which means little stress relief around the highest loaded holes, anisotropy which leads to higher stress concentration factors, low transverse strength, susceptibility to delamination, and sensitivity to environmental conditions. All of these factors together with the complexity of composite failure modes make the analysis and design of composite joints far more complex than that of metallic joints. Fatigue failure is the root cause which makes aircraft unserviceable. 75-80% of fatigue failures occur in the joints of structure, therefore researching joints is very important for improving aircraft life. Much effort has been put into solving the technical challenge for composite bolted joints.