The present invention relates to a kind of synthetic method of preparing 2-substituted indole derivatives, aromatic amine compound (I), ketone compound (II) and desiccant are mixed in organic solvent, after adding palladium catalyst, in aerobic Reaction under weakly acidic environment makes described indole compound (III), (I) is (II) is (III) is wherein R 1 selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkanoyl, C2-C6 alkenyl, C2-C6 alkynyl, halogen, hydroxyl, substituted or unsubstituted amino, substituted or unsubstituted phenyl, pyridyl and heterocyclic aryl; (1) also can be substituted or unsubstituted pyridinamine, pyrimidinamine, pyridazinamine or pyrazinamine; substituting group is selected from one or more C1-C6 alkyl, C1‑C6 alkoxy, C1‑C6 alkanoyl, C2‑C6 alkenyl, C2‑C6 alkynyl, halogen, hydroxyl, amino; R 2 Selected from C1-C6 alkyl group, formate group or C1-C6 alkanoyl amido group.