Utilizing silicon nanoporous pillar array (Si-NPA) as substrate, a kind of CdS/ZnO sesame-seed-candy structure was prepared by successively growing ZnO nanorods and CdS nanograins via chemical vapor deposition and successive ion layer adsorption reaction method, respectively. The capacitive humidity sensing properties of CdS/ZnO/Si-NPA were studied by constructing coplanar interdigital electrodes. With the relative humidity (RH) increasing from 11% to 95%, a capacitance response over 201,530% was achieved, which indicates that CdS/ZnO/Si-NPA is highly sensitive to humidity. The response and the recovery times were determined to be ∼110 s and 32 s, respectively, with a maximum hysteresis being ∼2.67% at 75% RH. The high humidity sensitivity of CdS/ZnO/Si-NPA is attributed to the enlarged specific surface area induced by its unique nanostructure, while the short response/recovery times and the small hysteresis were due to the channel network brought by Si-NPA. These results indicate that CdS/ZnO/Si-NPA might be an ideal material system for fabricating high-performance humidity sensors.