Abstract: The nonuniformness of wind load on the surface of shells compilcates the stability study of shells. With the aid of the Trefftz criterions the stability analysis for stiffener-reinforced cylindrical Shells under wind load is conducted. The effects of the stiffener eccentricity is also studied. It is observed that smooth shells is the most vulnerable, and the load-bearing ability of shells with circunferential ribs is better than that of shells with longtudinal stiffeners and the best load-bearing ability is acquired when shells are reinforced with both circumferential ribs and longitudinal stiffeners. It is also found that the load-bearing ability is in descending sequence for shells with outer ribs, shells with inner ribs and shells with central ribs on the shell skin