The invention relates to a norbornene, hexafluoropropylene and acrylonitrile ternary polymerization catalyst. The preparation method of the catalyst comprises the steps that (pentamethyl cyclopentadiene) cerium chloride and a ligand are dissolved into a first solvent in a dry three-mouth flask in the inertia atmosphere, titanium tetrachloride is dropped into the solution while stirring is performed, stirring is performed at the constant temperature of 30-60 DEG C for 30-60 min after dropping is performed, and a cerium-titanium complex catalyst is obtained. The polymerization method comprises the steps that a norbornene monomer, a hexafluoropropylene monomer and an acrylonitrile monomer are taken and added into a reaction kettle where repeated vacuumizing and nitrogen charging are performed, and a second solvent is added for dissolution; then, the cerium-titanium complex catalyst is added, a reaction is performed under the certain temperature and pressure, and the product is washed to obtain the terpolymer. Catalyst raw materials are low in price and easy to obtain, catalytic activity can be generated at low temperature, norbornene, hexafluoropropylene and acrylonitrile ternary polymerization is catalyzed, the reaction temperature is low, the catalysis efficiency is high, the copolymer yield is high, and the terpolymer is good in photoetching performance.