Abstract: Nitrogen (N) fertilizer reduction, crop yield sustainability and soil carbon sequestration are “win-win” strategies which are important for the sustainable development of ecological environment of regional agriculture. Based on a field experiment of red paddy soil, the effects of different fertilizations under the N reduction condition were studied on paddy soil productivity and fertilizer N agronomic efficiency (ANUE). Five fertilizer N treatments were as follows: control (CK), conventional N fertilizer (CF), 75% N fertilizer (DF), N fertilizer plus straw incorporation (RS), and N fertilizer plus manure application (OM). The results were as follows: the double-rice yield for treatments of DF, RS, and OM was 7.83 t/hm2, 7.26 t/hm2, and 8.05 t/hm2, respectively, and these values showed no significant differences with that for CF treatment (7.60 t/hm2). However, the double-rice yield for RS was significantly lower than those for DF and OM due to its decreased early rice yield, whereas no significant difference was observed between the latter two treatments. It indicated that N fertilizer plus manure application could sustain a more stable rice yield than straw incorporation under the N reduction condition. The ANUE for DF (13 kg/kg) was significantly improved by 30% than that for CF (10 kg/kg). As compared with DF treatment, OM could sustain the same ANUE (14 kg/kg), whereas RS (9 kg/kg) decreased ANUE by 31%, indicating that rice straw incorporation was not conductive to the utilization of fertilizer N under the N reduction condition. In addition, soil organic carbon (SOC) content at topsoil (0-20 cm) was not decreased by DF treatment, but was further increased by RS and OM due to the organic material input. In conclusion, 75% conventional N fertilizer could sustain both double-rice yield and SOC, and further promote the fertilizer N agronomic efficiency in the subtropical region. Under the condition of 75% conventional N fertilizer, the application of chemical fertilizer plus manure application could not only reduce the chemical fertilizer N use, but also show a better effect than rice straw in sustaining double-rice yield and fertilizer N agronomic efficiency.