Porcine pancreatic lipase (PPL) has been successfully immobilized in the mesoporous channels of SBA-15 with different pore diameters (6.7, 8.0, and 13.0 nm). The amount of enzyme adsorbed in the channel of the supports is found to be related to the pore diameters of SBA-15. It is observed that SBA-15 with a pore size of 8.0 nm is the most suitable support for the immobilization efficiency and immobilization capacity. Similarly, for the SBA-15 silylated with diisopropyl (DIP) groups, pore diameter also plays the same important roles in the immobilization efficiency and immobilization capacity. As for the activity of the immobilized enzymes, the pore dimension, the order of pore structure, and the surface property of the support make impacts.