Abstract: The relationship of TS-1 activity with time was investigated in a continuous epoxidation reactor, and the function curve of time to TS-1 activity was observed. The used catalyst was regenerated by calcinations.The results of the activity tests indicated that the activity of the regenerated catalyst was almost recovered.The fresh, the deactivated and the regenerated were characterized by a number of techniques such as SEM, N2 physical adsorption, TG, XRD, IR and NH3-PD.On the basis of the characterization, the mechanism of the deactivation was proposed.The deactivation of TS-1 can be attributed to the deposition of slowly diffusing organic by-products inside TS-1 channels. Additionally, small amount of titanium may be leached out from the framework of the catalyst.