Among the titanium alloys employed as implant materials, the Ti6Al4V alloy is still widely used. Micro-arc oxidation (MAO) was used to prepare ceramic oxide layer containing calcium and phosphor on surface of Ti6Al4V alloy and then the specimens were hydrothermal synthesis (HS) treated, and then a thin hydroxyapatite ((Ca-10(PO4)(6)(OH)(2), HA) film was deposited on the surface. The biocompatibility of Ti6Al4V alloy, MAO alloy and sample treated by hydrothermal synthesis were evaluated. The biocompatibility of three specimens was tested using anti-hematolysis tests, anti-coagulation tests, anti-platelet adhesion and cytotoxicity tests. Specimens coated with HA film exhibited significant improved anti-hemolytic reaction, and the hematolysis ratio was 0.994% (less than 5%), which indicated that this type of samples could not induce acute hematolysis. And coagulation did not occur within 50 min on the HA layer. There was almost no platelet adhered on the surface. The toxicity was ranked as 0 grades which indicated that it could not induce the cytotoxic effect. This demonstrates that the HA film can significantly improve the biocompatibility properties. (C) 2012 Elsevier B.V. All rights reserved.