The invention relates to compound quaternary ammonium salt disinfectant, which comprises dodecyldimethylbenzylammonium serving as a germicide, a double long-chain quaternary ammonium salt with high interference resistance and a synergist. The main technical characteristics of the compound quaternary ammonium salt disinfectant is the adoption of the high-safety mild and nonirritating poly(quaternary ammonium salt) which is formed by grafting C11 to C18 long-chain alkyl on the surface of an amino-terminated hyperbranched quaternary ammonium salt compound. The disinfectant can quickly kill board-spectrum fungi, saccharomycetes, mould, Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, virus and the like; with disinfection concentration, the disinfectant is low in toxicity and irritability; being noncorrosive, the disinfectant avoids corroding pipes made of stainless steel, copper, aluminum and the like; and the disinfectant has high biodegradability, avoids polluting the environment and meets requirements for environment protection. The disinfectant can be used for disinfecting surfaces of common objects and disinfecting food processing equipment, cotton and chemical fiber textiles, skin, adhesive films and the like.