Rice-tobacco(Yunyan87) of Hunan province was taken to determine the dynamic change of agronomic characters, root morphology parameter, leaf area index and the accumulation of dry matter, nitrogen, phosphorus and potassium, and to determine the utilization efficiency of nitrogen, phosphorus and potassium of flue-cured tobacco with different amounts of topdressing nitrogen (66.75 kg/hm2, 84.75 kg/hm2, 102.75 kg/hm2). The results showed that the dry matter and accumulation of nitrogen, phosphorus, potassium of flue-cured tobacco in rice stubble mainly allocated to tobacco leaf; with the growth of tobacco, the distribution ratio of the dry matter and accumulation of nitrogen, phosphorus, potassium in tobacco leaf became smaller; adding 10% nitrogen fertilizer promotes the growth of root system, improves agronomic characters; 90 days after transplanting, the leaf area index was respectively 2.38% and 10.58% higher than that of conventional topdressing and reduced nitrogen fertilizer, and the dry matter accumulation of leaves increased by 25.73% compared with the reduced nitrogen fertilizer treatment; nitrogen absorption efficiency was respectively increased by 24.52% and 12.82% compared with conventional topdressing and reduced nitrogen application, potassium absorption efficiency was respectively increased by 33.09% and 18.11% compared with conventional topdressing and reduced nitrogen application. Reduction of topdressing nitrogen will weaken root system and above-ground growth, reduce dry matter accumulation, and reduce nitrogen and potassium absorption efficiency. Therefore, for flue-cured tobacco from rice stubble in Hunan, the amount of topdressing nitrogen should be appropriately increased to improve the utilization efficiency of nitrogen, phosphorus and potassium.