The invention belongs to the technical field of high polymer material packaging, and particularly relates to an antibacterial composite polylactic acid preservative film material and a preparation method thereof. Through the design of a three-layer film structure, the purposes of preventing pathogens from polluting food and packaging materials, preventing harmful substances from breeding inside, maintaining the original flavor of the food, resisting bacteria and prolonging the shelf life are achieved. Through component modification of a polylactic acid film and application and bonding processdesign of the three-layer film structure, blocking, obstructing, prevention and control of pollutants and pathogens are performed from a food packaging source, the fresh-keeping treatment cost, the transportation cost and risk prevention and control of food are reduced, the comprehensive value of the food is improved, and the economic benefits, the social benefits and the environmental protectionbenefits are improved. The product is green, safe and degradable, can completely replace an existing polyethylene preservative film, and has wide popularization and application prospects.