Structural design parameters always impact the buckling properties of the composite shells due to the differences in the anisotropy of the materials and the varying enhancement capabilities of each component. This paper aims to analyze the parametric effect on the buckling load and optimize the design parameters of metal-composite shells with voids under hydraulic pressure. Firstly, the theoretical model of buckling load is established based on the microscopic model of hybrid materials and the Galerkin method. Then, four design parameters including fiber volume content, winding angles, and CNTs volume content are selected to discuss the parametric effect on the critical buckling load. Further, the global sensitivity analysis is conducted to determine the influence rank, and the GA-PSO algorithm is used to confirm the optimal parametric combination. The results imply that the fiber volume content and internal and external helical symmetrical angles significantly affect the buckling load. Besides, The winding layers of internal and external helical symmetrical angles enhance the hydraulic resistance of the anti-symmetric structure. The middle helical layer can be influenced by the outer layer, leading to directional changes in the critical buckling load at an angle of around 50°.