Abstract: In order to identify the relationship between nitrogen application rates and photosynthetic characteristics of cutters at topping stage in flue-cured tobacco, a pot experiment was carried out to study the effects of nitrogen levels on light response parameters of cutters at topping stage. Three levels of nitrogen fertilizer (45, 90 and 135 kg/ha) were set up in pot experiment. Net photosynthetic rate (P_n), intercellular CO₂ concentration (C_i) and transpiration rate (E) of cutters were measured in an open-circuit gas channel system, meanwhile, instantaneous light use efficiency (LUE_i) and instantaneous water use efficiency (WUE_i) were calculated out. The results showed that as the levels of photosynthetically active radiation increased, P_n of cutters at topping stage in flue-cured tobacco gradually increased and stabilized; as the levels of nitrogen fertilizer increased, P_n, C_i and LUEi of middle leaves decreased, and the same pattern was found on the apparent quantum efficiency (AQY), maximum net photosynthetic rate (P_max) and light compensation point (LCP). WUEi and light compensation point (LCP) were reduced with 45 kg /ha applied in pot experiment. Based on this study, an optimum nitrogen rate of between 45 kg/ha and 90 kg/ha was recommend to ensure strong photosynthetic capacity of cutters at topping stage in flue-cured tobacco.