Heterojunction solar cells (HSCs) with the structure of p-Si/n-ZnO nanorod (NR) arrays were prepared by synthesizing a ZnO NR array film on patterned p-type silicon substrate through a low temperature hydrothermal method. ITO and Al films as the front and back contact electrode layers were deposited by DC-magnetron sputtering, respectively. The influences of various factors, such as annealing temperature for seed layer and hydrothermal synthesis time for ZnO NR arrays, on the crystal structure, surface morphology, and optical property of the ZnO NR array film were investigated. Results show that the optimized short-circuit current density and allover energy conversion efficiency of the p-Si/n-ZnO nanorod array HSCs are 11.475 mA·cm^-2 and 2.0%, respectively. Compared with those of p-Si/n-thin film ZnO solar cell, the photovoltaic properties of the p-Si/n-ZnO nanorod array HSCs are improved significantly.