The tank of Reusable launch vehicle (RLV) is installed inside the body, forming a double layer structure. The stress characteristics of connection between inner tank and outer vehicle airframe is very important to reducing the structural weight、 improving reliability. In this paper，three kinds of connection scheme were put forward which are statically determinate structure and statically indeterminate structure， the finite element analysis method was used for the static analysis；and explore the effect of thickness on force transmission ratio. We draw a conclusion that the statically indeterminate structure joint scheme is more reasonable; it can adjust the axial load in the inner and outer layer by changing the thickness of structure. In this way, we can achieve the expected purpose.