This article listed the synthesis methods of nicotin ic acid.Among them, vapor-phase one-step oxidation and liquid-phase oxidation by catalysts were mai nly introduced. With proper promoters, 3-picoline can be directly oxidized with O 2 in vapor-phase into nicotinic acid in the presence of a V 2O 5 impregnate d TiO 2 catalyst. The highest yield of nicoticic acid was more than 90%.