Through the treatments of defoliate,darken ear and darken peduncle,we studied the effects of wheat photosynthesis organs on the 1000-grain weight and the contribution to 1000-grain weight in different quantity of N.The results show that the nitrogenous influence the 1000-grain weight,which is brought by both leaf organs and no-leaf organs;nitrogenous fertilizer can improve the 1000-grain weight,the contribution rate of 1000-grain weight.