The invention relates to phenoxy-2-iminoimidazolidine metal complex and a preparation method and application thereof. The preparation method comprises the steps of first, reacting oxalyl chloride with 1,3-dimethylimidazolidinone to obtain chloroformyl imidazole hydrochloride; second, reacting an amino-containing compound with the chloroformyl imidazole hydrochloride to obtain a ligand; third, subjecting the ligand and a nickel-containing catalyst precursor or palladium-containing catalyst precursor to coordination reaction to obtain the phenoxy-2-iminoimidazolidine metal complex. The phenoxy-2-iminoimidazolidine metal complex is used as a main catalyst, the main catalyst and a promoter jointly catalyze to polymerize norbornene, and the obtained norbornene is higher than 8*105g/mol in weight-average molecular weight and has narrow molecular weight distribution. The phenoxy-2-iminoimidazolidine metal complex prepared herein has high catalytic activity, may be 106-105 orders of magnitude under the action of the promoter, and is effective in catalyzing polymerization of norbornene.