Hydroxyapatite (HAp) is an inorganic material similar to human bone, with good biocompatibility. In this paper, HAp nanoparticles were in-situ synthesized using simulated body fluid (SBF) biomimetic mineralization method with graphene oxide (GO) as a template. The effects of mineralization time and volume ratio of SBF to GO on the phase composition, morphology, and structure of mineralization products were studied through testing and analysis of SEM, XRD, EDS and Raman spectroscopy. The results show that a large amount of uniformly distributed bone-like HAp is formed on the surface of GO after mineralization treatment. With the extension of mineralization time and the increase of volume proportion of SBF, the size and quantity of mineralization products increase, and the interlayer spacing of GO gradually expands. This study verifies the feasibility of synthesis of HAp nanoparticles assisted by graphene oxide, and expands the application field of biomimetic mineralization method.