The design of wing connection joint is one of the major parts in an aircraft wing design. The quality of the joints plays an important role in the operation safety and use life of an aircraft. Based on the center- outer wing connection joint design of foreign advanced civil aircrafts, two joint specimens were designed for the wing lower panels and joint rib. The connect strength and failure mode of joint specimens were studied. The failure process of the flange/ skin interface was simulated by using the cohesive element in the commercial software ANSYS. The research results indicated the debonding starting position of different joint specimens. The bearing capacity of joint specimens under pulling force and the bear strength of bolts were also researched. Finally an effective method was suggested for the design of composite key connection areas after comparing the two structural failure modes and load quantum.