Abstract: Using cationic surfactant of cetyltrimethylammonium bromide as templating agent, silicasol as silica source and aluminum sulfate as aluminum source, and auxiliary organic amines and hexane as additives respectively, the mesoporous molecular sieves MCM-41 were synthesized by hydrothermal method in basic media. The synthesized samples were characterized by XRD, N2 adsorption-desorption, and SEM. The experimental results show that, with the exception of triethylamine, after adding tri-n-propylamine, diisobutylamine tri-n-butylamine, tri-n-octylamine to reaction system respectively, the mesoporous MCM-41 samples attained have larger pore diameter compared with MCM-41 prepared without additives and have higher BET surface area and larger pore volume. Using hexane as auxiliary additive also can enlarge the MCM-41 pore diameter, but the sample have lower BET surface area (887.3 m2/g) and pore volume (0.81 cm3/g).