Abstract: In this study, double season rice Poyou 364 and Kyou 117 were used as test materials， the effects of different nitrogen application on double season rice yield， economic efficiency and nitrogen using efficiency were studied. The results showed that rice yield increased with the increase of nitrogen application rates in certain nitrogen range， and then decreased. The yield of early rice Poyou 364 was the highest at nitrogen application rate of 184 kg·hm-2， and the yield of late rice Kyou 117 was the highest at nitrogen application rate of 228 kg·hm-2. The equation between economic benefit of rice and N application rate was established based on the output of grain yield and input of fertilizer， as for early rice: y=-0219 7x2+75787x+2 9547， and for late rice: y=-0167x2+7107x+5 2028， According to the equation， the economic benefit of early rice Poyou 364 and late rice Kyou 117 were the highest at nitrogen application rate of 173 kg·hm-2， and 213 kg·hm-2, respectively. N uptake of grain increased， while N agronomic efficiency decreased， and N recovery efficiency showed a parabola curve with the increase of nitrogen application rates in double season rice. According to the principle of highyield， highefficiency and improving nitrogen use efficiency， optimal N application rate was recommended for double season rice.

Key words: nitrogen fertilizer application；double season rice, N uptake and use efficiency；optimization of nitrogen application