The invention relates to a gemini quaternary ammonium salt and use thereof. The quaternary ammonium salt is a compound as shown in formula I, and the formula I is described in the description, wherein R1 and R2 are respectively and independently selected from one of C6-C18 linear-chain or branched-chain alkyl or fluorine-containing C6-C12 linear-chain or branched-chain alkyl, Y is C1-C12 alkyl, and X is halogen or oxygen-containing acid radical. The gemini quaternary ammonium salt provided by the invention can be used for preparing an in-tank antimicrobial preservative for water-based paint.