Abstract: In order to explore the effects of different nitrogen fertilizer amount on grain filling rate of different pinnacle and grain positions, using‘nongda 3’as experimental material, under the condition of the same amount of phosphate and potash fertilizer, by changing the nitrogen fertilizer amount, the grain filling rate of different panicle and grain positions was studied. The results showed that the grain filling rate of different panicle positions was as follows: before grouting peak, whether it was the first branch or the secondary branch grains, the grain filling rate declined along with the lowering of the panicle position. After grouting peak, the filling rate of the first branch grains increased as the panicle position declined, the filling rate of the secondary branch grains was in an order of lower >middle > upper except under high fertilizer treatment (160-240 kg/hm2), which was middle > upper > lower. The grain filling rate of the same panicle position of the first and the secondary branch grains was as follows: before grouting peak, the filling rate the first branch grain was greater than that of the secondary branch grains; after grouting peak, the filling rate of the secondary branch grains was higher than that of the first branch grains. Grain filling rate of different panicle and grain positions showed an obvious unimodal curve, and the grain filling rate decreased with the increase of nitrogen fertilizer amount and the decline of panicle position.