Ti nanorod arrays with controllable density on titanium surfaces were prepared by tuning the content of oxalic acid. The field emission scanning electron microscopy (FE-SEM) and atomic force microscope (AFM) were used to analyze the topography and density of titanium nanorod arrays. Bioactivity was investigated by immersing the samples in a simulated body fluid (2SBF) for 3 and 5 d. Results demonstrate that the different densities of nanorod arrays result from the change of the concentration of H+. The approach herein can be developed to be a facile nanotechnology for nano-functionalization of titanium. The structure of titanium nanorod arrays promotes the growth of calcium phosphate on the surface of the titanium, the mineralization ability is the best at density of (1.79 ± 0.04)×1010/cm2. By this token, the nanostructure facilitates the osseointegration between the bone tissue and implant, and subsequently improves the performance in clinic