Abstract: To clarify the effect of topdressing time of nitrogen and water on stem traits and yield of winter wheat, the field experiment was designed with seven topdressing time of nitrogen and water with winter wheat cultivar‘Jing 9428’as material, the stem straits, yield and its composition of winter wheat were studied in the experiment, and the relationship of grain yield with yield components and stem straits of winter wheat was analyzed. The results showed that the nitrogen fertilization and irrigation were applied when the third or fourth spring leaf emerged, the bottom first or second internode was elongated significantly, the uppermost internode length was significantly short, the plant height was significantly small, the number of head per hectare and grain number per head were significantly less, and the yield was significantly low. But in contrary, if nitrogen fertilization and irrigation were applied in the stage of the spring five leafs after irrigated in the stage of spring three or four leafs, longer bottom internode could be expected. The effects of the other treatments were not significant. The top function leaves Pn was enhanced significantly after irrigation or topdressing nitrogen, compared with that at the third or fourth stage, topdressing nitrogen and water at the fifth leaf stage enhanced significantly the Pn after the blossom. The effects of different topdressing time of nitrogen and water on stem number and dry matter per plant were little. It is suggested to carry out fertilization and irrigation in the stage of spring three or four leafs, and supplying fertilization in the stage of spring five leafs in this area.