Silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure with regularly patterned surface morphology. Through a heterogeneous reaction process, zinc sulfide nanocrystallites (nc-ZnS) were grown onto Si-NPA and a unique heterostructure of ZnS/Si-NPA was obtained. The formation of wurtzite nc-ZnS was proved by x-ray diffraction, and the average grain size was evaluated to be ∼18 nm. X-ray photoelectron spectroscopy disclosed that as-grown nc-ZnS was well separated from Si-NPA by a SiO2 thin layer of ∼1.3 nm. The photoluminescence (PL) spectrum of ZnS/Si-NPA showed that in addition to the two red PL bands peaked at ∼648 and ∼705 nm observed in Si-NPA, three other PL bands peaked at ∼365, ∼418, and ∼472 nm were observed and attributed to the PL from nc-ZnS. It was also demonstrated that as-prepared ZnS/Si-NPA heterostructure could exhibit good rectification characteristic featured by a high forward current density of ∼75 mA/cm2 at 2 V and high reverse breakdown voltage of ∼10 V. Our results indicated that ZnS/Si-NPA might be a valuable heterostructure nanosystem to be further probed for achieving enhanced optical and electrical properties.