Titanium and its alloys are standard for orthopedic prosthetic devices, due to their good mechanical properties and biocompatibility. However, bioactivity on the implant surface needs to be improved to achieve an optimal osseointegration process. Metal implants are often coated by hydroxyapatite because they have a chemical composition and crystal structure similar to apatite in the human skeletal that suitable for bone reconstruction. The focus of this research is on surface treatment designed to promote better biological responses through hydroxyapatite layers. Also combining the acid etching treatment of Ti-6Al-4V and the electrophoretic coating process of the hydroxyapatite to obtain stronger mechanical interlocking interface. Hydrofluoric-Acid treatment conducted in various time. Then, coated with nanosized hydroxyapatite through electrophoretic deposition at 15V voltage for 10 minutes. Scanning Electron Microscopy and Contour measurements were performed to show the surface topography indicating the formation of surface contours with increasing surface roughness parameters in accordance with the time of the etching process. The contours on the surface of the substrate induce the mechanical interlocking of the surface so that the results of hydroxyapatite deposition optimal at the time of etching 5 minutes.