This paper proposed a damage detection method based on Dempster-Shafer (D-S) evidence theory to get the damage diagnostic result of an ancient Chinese tower. Three individual vibration-based damage identification methods are used to analyze the damage states initially. To reduce the uncertainties on each damage detection method, a modified D-S combination rule is carried out by combining the acquired diagnosis results. Ultimate diagnosis decision is made according to the maximum belief. Numerical results indicate that compared with conventional diagnostic methods, the improved damage detection method can enhance diagnostic accuracy effectively.