Objective: The aim of this study was to clarify the effects of baicalin on the biological properties of human periodontal ligament cells. Materials and Methods: Effects of baicalin on proliferation, alkaline phosphatase activity (ALPase activity), the synthesis of the total protein and ultrastructure of human periodontal ligament cells were examined in this study. Culturing PDL cells in vitro, MTT assay, coomasie brilliant blue staining, ALPase kit and transmission electron microscope were involved in this research. Results: The range of 0.01～100ng/ml baicalin enhanced the proliferative response of PDL cells. The maximum mitogenic effect of baicalin on PDL cells was observed at the concentration of 10ng/ml. The proliferative response was minimal at 1 d, but marked at 3 d and 5d. The range of 1～1000ng/ml baicalin may enhance the synthesis of the total protein of PDL cells, which also marked at 3 d and 5d and the response has a dose-dependent and time-dependent manner in the range of 1～100ng/ml baicalin. The optimal effect of baicalin was observed at the concentration of 100ng/ml, when more than 100ng/ml of baicalin was added to the culture, the total protein of PDL cells decreased. 10～100ng/ml baicalin could increase the ALPase activity. Moreover, 10ng/ml baicalin could increase the number of mitochondria and rough endoplasmic reticulum of PDL cells. Conclusion: The results showed that baicalin could increase the proliferation and the synthesis of the total protein of PDL cells, which suggested that it might play a role in accelerating periodontal tissue regeneration.