Folic acid compounds receptors are overexpressed on the surface of some human tumor cells, while they are rarely expressed in normal tissues. They have the potential to be targeted for cancer therapy, and experiments have shown that they can also provide targets for tumor imaging. Folic acid compounds have advantages such as low cost, high biological and chemical stability, physiological compatibility, and high receptor affinity, making them promising carriers for tumor diagnosis and treatment drugs. The purpose of this invention is to propose a method for the preparation of folic acid compound-mediated active targeting carriers. This invention uses the tosylate ester method to activate polyethylene glycol, ultimately converting the terminal hydroxyl groups into amino groups, forming bis-aminoethylene glycol, which then reacts with activated polylactic acid copolymers. The amino groups are then used to connect with folic acid compounds, completing the synthesis of complexes between folic acid compounds and polylactic acid copolymers. Specifically: The molecular weight of polyethylene glycol is 3000-10000.