The invention belongs to the field of polymer materials and technical synthesis thereof, and particularly relates to 1,3,5-tris(4-aminophenylmercapto)benzene as well as a preparation method and application thereof. Thioether bonds are introduced into a triamine monomer to obtain 1,3,5-tris(4-aminophenylmercapto)benzene; and 1,3,5-tris(4-aminophenylmercapto)benzene and dianhydride, dianhydride and tetrachlorophthalic anhydride, or dianhydride and 3,5-dichloroaniline are taken as raw materials to prepare an anhydride-terminated, tetrachlorophthalic anhydride-terminated or 3,5-dichloroaniline-terminated A2+B3 type hyperbranched polyimide. According to the invention, the 1,3,5-tris(4-aminophenylmercapto)benzene monomer contains thioether bonds, so that the sulfur content of the hyperbranched polyimide is increased, and the thermal stability, solvent resistance, high refractive index and the like of the polymer are improved. Meanwhile, the branched structure and the end groups of the hyperbranched polyimide can be subjected to termination modification, so that the hyperbranched polyimide has a wide application prospect in many fields.