In this paper, ZnO nanorods were grown by wet chemical method on p-Si (100) substrate to form n-ZnO nanorods/p-Si (100) heterojunction. The optical, electrical, structural properties of n-ZnO nanorods/p-Si(100) heterojunction were analyzed by the photoluminescence (PL) spectroscopy, [Formula: see text]–[Formula: see text] measurement, X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The room temperature PL spectra reveal the good optical property of the heterojunction with strong UV peak at 385[Formula: see text]nm. The ZnO nanorods were vertically well-aligned on p-Si (100) and had an average height of about 1.6[Formula: see text][Formula: see text]m. The n-ZnO nanorods/p-Si (100) heterojunction also exhibits diode-like-rectifying-behavior.