The invention relates to a composite multifunctional chemical plugging agent, which is composed of an organic multifunctional plugging agent, an inorganic multifunctional plugging agent and a composite synergist. The main components include carbon 7-10 aromatic hydrocarbon organic solvents, polyoxyethylene ether surfactants, oil-soluble water-dispersed polyether demulsifiers, T penetrants, polyether wetting agents, mutual solvents, and insoluble scale conversion agents , organic / inorganic compound acid, cationic polymer clay stabilizer, water-soluble polyether demulsifier, iron ion stabilizer, polyether wetting improver, dissolution aid, slow corrosion inhibitor, cationic polymer Sand stabilizer, etc. Inject 50-100% aqueous solution of organic multi-functional plugging remover, 5-35% aqueous solution of inorganic multi-functional plugging remover, and 25-35% aqueous solution of composite synergist into oil-water wells according to the usual method of using plugging remover, To play their respective effects and synergistic effect, the retarding effect of the plugging agent is excellent, which is 10 times that of conventional earth acid.