Abstract: The joint of a composite sandwich structure with a composite connection-mode has advantages such as lightweight, anticorrosion and no magnetism. The experimental studies on the bending performance of insert adherence composite joints were carried out. The effects on the load-deformation behavior, strain-developing, failure modes from the fiber layout in the connection-mode and laps of splice were mainly investigated. The test results show that there are three types of failure modes, which include debonding failure between surface-layer and core material, debonding failure between overlaps and debonding failure between surface-layer and core material in variable cross-sections. It can be known that the configurations and lay-up design in the connection-mode, length of overlap mainly affect its strength. The failure mechanism of insert adherence joints was discussed. The results can be referred for the design of composite joints with a composite connection-mode.