Abstract: In order to promote the application of organic manure and chemical fertilizer in the rotation of Flue-cured tobacco rationally, the effect of different organic manure (crop straw, oil cake, fully-fermented pig manure) applied in preceding crops on availability of nitrogen fertilizer was studied by the methods of pot and micro plot experiment in field, using the Isotope 15N trace technique. The results showed that all treatments promoted the growth of flue-cured tobacco and affected the nitrogen utilization. The effect of different kinds of organic manures on total nitrogen in leaves was different. After oil cake and fully-fermented pig manure were applied during preceding crop, percentage of absorbed nitrogen in different position from 15N fertilizer was increased, and the nitrogen fertilizer efficiency was also enhanced. Organic manure applied in preceding crops could raise the usability of the upper leaves and improve the cutters quality, compared with control. The conclusion was that oil cake and fully-fermented pig manure applied in preceding crops were better to flue-cured tobacco.