To construct hydrophobic containment vessel (CV) surface to enhance heat transfer capability under accident conditions, porous microstructures with various diameters and heights on silicon wafers were systematically prepared, and the hydrophobic mechanism of the microstructures were investigated. Results show that the wetting characteristics of all the samples belong to the CassieBaxter model. The hydrophobic properties can be effectively improved by microstructure modulation, and the contact angles are dramatically enhanced from 69.5° to 140° without chemical modifications. The results provide solutions for design of coating materials in CV, as well as the methods for enhancing the heat transfer performance of passive containment cooling system in a nuclear power plant.