The present disclosure discloses polyester composites and their preparation methods, and belongs to the technical field of polymer processing and modification. The polyester composites of the present disclosure comprise 65 to 90 parts of polyester, 5 to 35 parts of an elastomer, 0.05 to 3 parts of a chain extender and 0.01 to 5 parts of a functional additive. The polyester composites of the present disclosure not only have ultra-high toughness, but also can maintain high tensile strength, have excellent hydrolysis resistance, can be matched with an antibacterial agent or an antistatic agent to have good antibacterial or antistatic additional functions, can be widely applied to the fields of fibers and fabrics, plastic structural parts, plastic packages or automobile interior parts, and have a wide prospect.