In the paper, Ti6Al4V substrates have been pretreated with sodium hydroxide (NaOH) solution. After that, hydroxyapatite (HA) is deposited on the Ti6Al4V surface by electrochemical methods. The aim of this study is to investigate the influences of current density on the coating compositions, microstructure, and bonding strength between coating and substrate. The results show that the composition of the HA coating and the grain size remained relatively unchanged with the variations of current density during electrochemical deposition. When the value of electrochemical deposition current density is 2.5 mA/cm2, the HA coating has the largest thickness, and the bonding strength is near 18 MPa. The experiments of the samples being immersed into simulated body fluid estimate that the HA coating promotes the deposition of calcium phosphate. The formation mechanism of HA coating on modified Ti6Al4V deposited by electrochemical method is discussed.