Tetrabutylammonium fluoride or abbreviated as: TBAF is a quaternary ammonium salt, with chemical formula (CH3CH2CH2CH2) 4n+f-). This compound of the tri-hydrate or its tetrahydrofuran solution belongs to commercially marketed reagents. In the laboratory, the four hydrogen furan solution of tetrabutylammonium fluoride is often used in organic soluble fluorine ions, which can be removed from the silicone ether protection base. It can also be used in phase transfer catalysts and a mild alkali. By heating, the compound can also react to N-alkylation of acyl ammonia. Since the fluorine atom is a strong hydrogen bond receptor, it is almost impossible for the compound to get a completely dry sample. When heated to 77°c in a vacuum, the compound is decomposed into hydrogen fluoride root salts, and when the sample is dry at 40°c in a high vacuum, the 10-30mol% moisture content and 10% of two fluorine salts are still obtained.