Thrombogenesis is the principal problem associated with blood-contacting biomedical devices. One of the important reasons is that most of the materials used in these devices cannot avoid inducing platelet adhesion and activation. Our recent investigation suggested that Ti-O thin film could be an alternative antithrombotic material. In this work, we focus our attention on behavior of platelets adhered on Ti-O film. Platelet adhesion experiments were conducted to examine the platelets/material interaction in vitro and the effect of protein adsorption on platelet adhesion and activation. The specific resultants of platelet release (GMP140) were tested for evaluating the platelet activation. In vivo implantation was used to investigate formation of thrombus. The excellent anticoagulation performance of Ti-O films has been shown in in vivo long-term mplantation. The release of specific resultants GMP140 from platelets contacting to Ti-O film was the lower than LTI-carbon. The morphology of adherent platelets maintainsround and isolated. Apparently, the activation of platelets adhered on Ti-O film was suppressed. The results of in vitro test also suggest that the suppression of platelet activation is related to plasma protein adsorption. Preadsorbing fibrinogen doesn't cause the exacerbation of platelet activation. It seems reasonable to suggest that its excellent anticoagulation is caused by inhibition of adherent platelet activation produced by Ti-O film.