Photoassimilates partitioning was studied using the experimental data of winter wheat in 2008-2009 at irrigation experimental station of Tianjin Agriculture University.The Research showed that when relative development stage (RDS) was greater than 0.35 fr(root), fr (stem and sheath) and fr(leaf) decreased ,fr(Ear) increased with the increase of RDS,and turned into negative When RDS were 0.59,0.67,0.7 respectively.It was due to the existence of repartitioning of photoassimilates, and photoassimilates storaged in root , stem and sheath and leaf began to transport to ear.Water and nutrition had a certain influence on the partitioning of photoassimilates among organs.Excessive water and nutrition were unfavourable for the transportation of photoassimilates to the growth center.