In this paper, the instability paths of two typical structural systems of Chengdu airport terminals, composed of single-layer reticulated cylindrical shell and supporting system, were investigated by non-linear analysis program based on Beam-Column theory, considering the vertical symmetric load combination, vertical asymmetric load combination and wind load combination.The results indicate that, compared with the single-layer reticulated cylindrical shell, both the ultimate load bearing capacity and the sensitivity of geometric imperfection of the whole structural system will decrease.