The invention discloses thermoplastic polyester for an antibacterial film. A whole polyester reaction is divided into preparation of three different prepolymers, and then the three different prepolymers are subjected to polycondensation to obtain the polyester. The thermoplastic polyester has the advantages of being uniform in molecular weight and high in physical stability; meanwhile, due to the fact that introduced groups with various functions are polymerized in different steps, mutual interference is greatly reduced, and a more stable effect is achieved. The prepared thermoplastic polyester material has good fire resistance, antibacterial performance and high strength even after being used for a long time.