In order to provide scientific theoretical basis for green manure utilization and nitrogen fertilizer application in southern rice, based on the field localization experiment in 2016, the influence of different nitrogen application rates (N0:no nitrogen application; N50:50% reduction in nitrogen; N100:conventional nitrogen; N150:50% increase in nitrogen application) on yield, nutrient uptake characteristics and nitrogen efficiency of double-cropping rice were explored in the two modes of fallow (F) and green manure (G). The results showed that compared with the fallow mode, the green manure mode of winter planting increased the yield of early and late rice under these four different nitrogen levels, and the yield of early and late rice increased by 8.0% and 5.7% on average. In both modes, the yield of early rice increased firstly and then decreased with the increase of nitrogen application, while the increase of late rice showed an upward trend. The green manure model of winter planting also increased the accumulation of nitrogen (N), phosphorus (P), and potassium (K) in the aboveground part of the plant and the partial productivity of nitrogen fertilizer. With the increase of nitrogen application, the nutrient harvest index and nitrogen fertilizer utilization rate of early and late rice in these two modes mostly showed a downward trend, and the high-level nitrogen fertilizer treatment (N150) reduced the accumulation of aboveground K elements in the early rice season. There was a significant positive correlation between early and late rice yields and N, P and K accumulation, and the decrease of high nitrogen treatment (N150) K uptake in the two modes was associated with the decline of early rice yield. Comprehensive consideration combined with the fitting analysis of rice yield and nitrogen application rate, nutrient absorption, and utilization, etc., the suitable application range of nitrogen fertilizer in early rice season was 150.0 to170.3 kg/hm² under the fallow mode, and 75.0 to 122.8 kg/hm² in early rice season under winter green manure mode. Therefore, in the double-cropping rice area of southern China, planting green manure in winter can increase the absorption of N, P, and K elements in rice, and can reduce nitrogen fertilizer without reducing the yield of double-cropping rice in the early rice season, which is of practical significance for achieving efficient rice production.