In this paper, the thermal insulator structure of a real rocket which is fabricated in a way that laminated composite rings are connected in series is analyzed using 3-dimensional axisymmetric finite element models. Simulation of cowl zone using real operating conditions provides that the stress distribution in the laminated composite ring is largely influenced by ply-angles, axial dimensions, and boundary conditions. It is hypothesized that notably the ply-lift that is the precursor to the wedge-out occurs in the ring-to-ring bonding region to a limited ply angle. Moreover, it is suggested that the wedge-out is dropped out due to the maximum shear stress in a fixed ply-angle direction and the axial compressive stress.