The invention relates to a preparation method of a high-performance hollow-fiber organic gas separation composite membrane applied to the technical field of organic gas separation and recycling. The preparation method includes: using a hollow-fiber membrane sold on the market as the base membrane, cleaning, and coating the hollow-fiber membrane with a silane coupling agent solution for the first time; dissolving polydimethyl siloxane into a solvent, evenly mixing, adding a crosslinking agent and a catalyst, performing standing and defoaming to obtain coating liquid, and coating the hollow-fiber membrane with the coating liquid for the second time to obtain a hollow-fiber PDMS composite membrane; activating the PDMS composite membrane, and placing the surface-activated PDMS composite membrane into the organic solvent of silane monomers to perform surface grafting polymerization to obtain an organic silane polymer ultrathin surface layer so as to obtain the high-performance hollow-fiber organic gas separation composite membrane resistant to steam and organic solvents and high in organic gas selective permeability. The preparation method is simple and suitable for industrial production.