The invention discloses a method for gradually replacing tobacco nitrogen fertilizers with multicropping vetches. The method comprises the following steps of hole-sowing a row of Yunguang early vetches on each of two sides of tobaccos on a tobacco planting ridge, and cradling, chopping, turning and pressing fresh Yunguang early vetches in early March of the next year at the period of full bloom, wherein the using amount of low- and medium-fertility soil is 15,000 kg/hm<2>, and the using amount of high-fertility soil is 7,500 kg/hm<2>; aftercropping the tobaccos, and continuously multicropping the tobaccos and the vetches. Compared with the using amount of conventional fertilizer application, the using amount of tobacco nitrogen fertilizers is reduced by 15 percent in the first year and is progressively decreased year by year on the basis of the using amount of the last year according to 15 percent until the using amount of the nitrogen fertilizers is progressively decreased to zero. According to the method, the using amount of the tobacco nitrogen fertilizers is greatly reduced; furthermore, the yield of tobacco products can be obviously improved and is increased by over 10 percent; the quality of the tobacco products is obviously improved; the output value is increased by over 14 percent; the effect of improving the soil is outstanding; the average annual increase of organic matters in the soil is 0.025 percent; the average annual decrease of the volume weight of the soil is 0.011 g/cm<3>.