Abstract: Effect of N and K fertilizer application amount on the population quality and the yield of single cropping medium rice were studied using medium japonica wandao 68 as materials and establishing different N and K fertilizer application amount.The results show that when the grain output of amount of N and Kcl applied was262.5kg/hm2 and 375.0kg/hm2,the yield was 11211.1kg/hm2 was tiptop.The total tillers ,LAI, dry matter accumulation and the yield components were very significantly increased in pace with increasing N application amount,but the grain output of amount of nitrogen applied was262.5kg/hm2 was tiptop on spiking rate of tillers,percentage of effective and high effective LAI,dry matter after heading and total spikelets. K fertilizer on rice panicle and grain per spike few little effect on the firm can increase the seed-setting rate and 1000-grain weight,with the increase in K application amount, Percentage of the toppest joint and panicle lengh to plant height and production on dry matter after heading were increased and was conductive to raising lodging of plants,the population quality of the rice and yield were increased ,but not significant.