The invention discloses high polymer and a preparation method of high polymer and nano-fiber thereof. The polymer is copolymer which is polymerized by at least a vinyl halogenated phenols monomer A, at least a vinyl tertiary amine monomer B and at least a monomer C with cross-linkable group. Monomer A, monomer B and monomer C make polymerization in the presence of initiating system. The reaction temperature is 40-120 DEG C and reaction time is 4-24 hours; the objective copolymer is obtained by precipitation, filtration and drying after the reaction. The solvent-resistance nano-fiber can be prepared after electrostatic spinning and crosslinking treatment of the polymer. Since the molecular structure of the polymer and nano-fiber contains halogen phenol group and tertiary amine group which can be mutually bonded to form quaternary ammonium salt, the polymer and nano-fiber of the invention has excellent antibacterial performance; meanwhile the nano-fiber is crosslinking structure, so thenano-fiber has excellent solvent stability.