Highly ordered and size controllable ZnO nanorod arrays were prepared on Ti substrate through a hydrothermal method, and then the biocompatible PDLLA coating was self-assembled onto the surface of the prepared nanorod arrays via electrostatic adsorption process. SEM, MTT and LDH methods were used to characterize the morphology and biological activity of cells. The results show that cells on the ZnO nanorod arrays are round-like without spreading; while after the modification of PDLLA, there are the largest amount of cells on the modified nanorod arrays, the extracellular matrix become well-spread with many filopodia embedded into the gaps of the array structure, and the cell activity is significantly higher than that of ZnO nanorod arrays and titanium film. It is concluded that the PDLLA coating can improve the biocompatibility of the material to provide a suitable microenvironment for cell growth, and effectively promote the adhesion and proliferation of cells.