Abstract: Objective: To investigate the cytocompatibility of ultrasonic micro-arc oxidation-sodium alginate- chitosan composite coating on pure titanium. Methods: The specimens in our research were divided into 3 groups: pure titanium ultrasonic micro-arc-oxidation (group A); pure titanium ultrasonic micro-arc-oxidation chitosan group (group B); and pure titanium ultrasonic micro-arc-oxidation-sodium alginate-chitosan group (group C). Scanning electron microscope was used to observe the surface morphology. CCK 8 experiment was used to detect the adhesion rate and proliferation of osteoblasts. Laser confocal microscopy and scanning electron microscope were used to detect cytoskeleton microfilament stretch and surface morphology of osteoblasts. ALP test was used to evaluate the alkaline phosphatase activity. Results: CCK 8 test showed that, with the extension of time, the OD value of group A, B, and C were increased and in the turn at C>B>A. CCK 8 hyperplastic experiments showed that the proliferation rate of group C and B were better than that of group A. Confocal laser microscope showed the cytoskeleton form. In a certain period of time, the spreading area and the number of microfilament and pseudopodia of group C were the best. The ALP activity was significant higher in group C and in the turn of C>B>A (P<0.05). Conclusion: All three materials showed harmonious cytocompatibility, and the best was the ultrasonic micro-arc oxidation-sodium alginate-chitosan composite coating.