Abstract: A field experiment was conducted to evaluate nitrate accumulation, crude protein (CP) content and nitrogen use efficiency of sweet sorghum (Sorghum bicolor cv. Hunnigreen) under different nitrogen fertilizer rates (0, 100, 200, 300, 400, 500 kg N/ha) in 2009 and 2010 in eastern China. The experiment was laid out in randomized complete block design with three replicates. Nitrate content of shoot decreased with plant growth and nitrate accumulation was higher in stems than leaves. The crude protein production efficiency (CPPE), nitrogen dry matter production efficiency (NDMPE), dry matter production efficiency (DMPE) and nitrogen apparent recovery rate (NARR) decreased with increasing rate of nitrogen fertilizer, indicating that the higher rates of nitrogen decreased nitrogen use efficiency and increased nitrogen losses. Crude protein (CP) and free amino acid (FAA) content increased with increasing rates of nitrogen. However, the increase of FAA was much less than that of CP. Mean CP content was 6.11%, while FAA content was 2.99% when nitrogen was applied at 500 kg N/ha, indicating that the application N increased the CP content, but decreased the proportion of high quality protein. Nitrate content of sweet sorghum increased with increasing rates of nitrogen, however, it was not above toxic levels, 0.2% of DM (dry matter), until application rates were above 400 kg N/ha. The most appropriate rate of nitrogen for sweet sorghum in eastern China was 200-300 kg N/ha; these rates increased the yield and quality of sweet sorghum, improved nitrogen use efficiency and also reduce nitrogen losses and nitrate contamination in soils and groundwater.