A field experiment was conducted in Taihu Lake region to study the effect of a fertilizer additive on rice growth, yield and nitrogen use efficiency. The results showed that the fertilizer additive significantly increased rice biomass by 17.95%, 8.63% and 11.09% at heading stage and by 2.16%, 12.13% and 11.47% at filling stage respectively for N application rates of 150, 200 and 250 kg/hm2 respectively. This fertilizer additive also significantly increased root biomass by 7.21% - 27.40% at elongation stage under different N application rates. Yield increase was not as high as biomass, but increased significantly under 250 kg/hm2 treatment, being 5.79%. The fertilizer additive apparently increased rice N uptake, agronomic N use efficiency (AE) and apparent N recovery efficiency (NRE), and the increase was significant under high N application rate, being 7.14%, 33.26% and 10.91% respectively under 250 kg/hm2 treatment.