By using a self-designed loading device,the interface performance of CFRP ( Carbon Fiber-Reinforced Polymer) -C60 high-strength concrete under different bond lengths are investigated via double shear tests.Then,the concept of the minimum bond length is proposed and a model of the effective bond length is established.The results indicate that ( 1) with the increase of the bond length,both the ultimate bond load and the ultimate global slip response increase remarkably ,while the initial strip load and the initial strip response have no significant change; ( 2) with the increase of the load，the stress transfer area moves forward from the loading end and continuously prolongs,which presents a process of dynamic change; ( 3) the minimum bond length of C60 concrete is about 2 times the effective bond length; and ( 4) when the bond length is larger than the minimum value,the bearing capacity of the concrete can be fully used and the ductility is improved.