Delaminations may greatly reduce the buckling load of the laminated structure. Cylinder including arbitrary delaminations in longitudinal and thickness and spaning the entire circumference was divided into multiple sublaminates shell whose longitude displacements were simulated with linear function of the thickness coordinate. The variational principle was applied to obtain the governing equations and boundary conditions. The state-space scheme was used to solve the problem. By comparing with classical theory, the usable range of each theory was pointed out. Three difference buckling modes of delaminated shell were considered. The influence of boundary condition, length and depth of delamination on buckling load was analyzed. Finally, the buckling analysis of delaminlated orthotropic shell was given.