The invention discloses an artificial UHMW (ultra-high-molecular-weight) antibacterial polypeptide and a preparation method thereof. A divalent organotin and trace divalent copper composite catalyst is used to replace a traditional monovalent copper catalyst, and the artificial UHMW polyacrylate antibacterial peptide with a better antibacterial effect is synthesized. The synthetic polymer antibacterial agent has efficient targeted antibacterial property and biocompatibility, cannot be degraded easily and has very good antibacterial activity on bacteria. Besides, the polymer antibacterial agent cannot cause generation of agent-resistant bacteria, cannot infiltrate into skin and pores of a human body, and is an ideal substitute of antibiotic drugs.