The invention provides an N,N-single ligand metal catalyst with three-dimensional structure and a preparation method thereof. The catalyst has a structural general formula as below. Mt represents nickel, palladium, cobalt, iron or copper metal atom; R1 represents bromine, chlorine, iodine, phenyl group, propyl group, butyl group, phenyl group, naphthyl group, methoxy group or ethoxy group; when R2 is aromatic amine, it represents aniline, naphthylamine, p-methylaniline, p-chloroaniline, p-fluoroaniline, p-fluoroaniline, p-bromoaniline, p-nitroaniline, o-bromoaniline, o-chloroaniline, o-nitraniline, 2,6-dichloroaniline, 2,6-difluoroaniline, 2,6-dibromoaniline, 2,6-dinitroaniline, 2,6-dimethylaniline, 2,6-diisopropyl aniline, 2,4-difluoroaniline, 2,4-dibromoaniline, 2,4-dichloroaniline, 2,4,6-trichloroaniline, 2,4,6-tribromo aniline, 2,4,6-trifluoroaniline, 2,4,6-trinitroaniline, 6-hydroxynaphthylamine, 1-aminoindan, fluoreneamine or 4-nitro naphthylamine; and when R2 is aliphatic amine, it represents ethylamine, propylamine, butylamine, heptylamine, isopropylamine, tert-butylamine or cyclohexylamine. The preparation method is simple, less in by-products, and environmentally friendly.