MCM-41 modified with tetrabutyltin and Sn-O-MCM-41 obtained from calcination of the modified MCM-41 in pure oxygen were characterized by XRD, FTIR, UV-Vis DRS, and TG analysis. It was found that the hydrothermal stability, surface acidity, and coordinative states of tin atoms on both samples were evidently different. After calcination, the surface tin atoms of sample remained in the tetrahedronal structure, and the hydrothermal stability and surface acidity were improved. According to the results, the reason for the enhancement of catalytic activity of Sn-O-MCM-41 was discussed.