To explore the effects of nitrogen and phosphorus on nitrogen use efficiency and starch quality of weak gluten wheat，three phosphorus levels(P1:60 kg/hm²，P2:120 kg/hm²，P3:180 kg/hm²，P2O5)were set up at the two nitrogen levels of 120 kg/hm² (N1)and 180 kg/hm²(N2)，respectively，and the effects of nitrogen and phosphorus on nitrogen uptake and utilization，grain starch size distribution and viscosity parameters of weak gluten wheat plants were analyzed using Ningmai 13 as the experimental material.The results showed that the accumulation of nitrogen per plant in flowering stage and that of plant and grain in mature stage increased significantly with increasing P application.There was no significant difference in the amount of nitrogen translocation per plant in the pre anther vegetative organs at N1 level，and the amount of nitrogen accumulation per plant increased first and then decreased with the increase of phosphorus application at N2 level，with no significant difference between N2P2 and N2P3.The transport rate and contribution rate of nitrogen from the vegetative organ to the grain at N2 level were significantly lower than those at N1 level.The increase of P application was not conducive to the increase of the transport rate and contribution rate of nitrogen from the vegetative organ to the grain. The nitrogen production efficiency and nitrogen use efficiency at N1 level were higher than those at N2 level.The increase of P application increased the nitrogen production efficiency，but decreased the nitrogen use efficiency.P application affected the size distribution of starch granule in weak gluten wheat，more P application increased the volume and surface area percentage of A type starch granule，decreased the volume and surface area percentage of B type starch granule，and increased the parameters of peak viscosity，valley value viscosity，final viscosity，disintegration value and recovery value of starch.The results showed that the increase of P application significantly increased the nitrogen accumulation in plant and grain and the nitrogen accumulation in vegetative organs and grain immediately after anthesis，and then increased the nitrogen production efficiency.The increase of P application was significantly conducive to the increase volume and surface area percentage of A type starch granule，and then increase the viscosity parameters of starch in wheat.