Abstract: TiN film was deposited on TC4 titanium substrate by reactive magnetron sputtering method.Adhesion strength of TiN film and substrate was measured by scratching method.The critical load determined by scratching method and microscopic method was contrasted and analyzed combined with hardness data.The results show that it was restrictive to judge the critical load only relying on scratching method.It would be more scientific and reasonable to judge the critical load by scratching method combined with microscopic method and mechanical properties such as hardness.