Trimethylchlorosilane as a modifier and tetraethoxysilane, an acid catalyst, as raw material were modified hydrophobically through the copolymerization, surface derivative, and hierarchical hydrophobic modification methods. The modified material was prepared as hydrophobic SiO2 aerogels by constant pressure drying. Finally, thermal stability, pore structure, and chemical composition of SiO2 aerogels were analyzed using TG-DSC, FTIR, and BET. The results show that the hydrophobic property of SiO2 aerogels prepared using hierarchical hydrophobic modification and surface derivative methods have excelled characteristics, such as super-hydrophobicity. The aerogels prepared through the two different methods have a mesopore structure with mesopores of 2–70 nm; however, they have no micropore structure.