The effects of different phosphorus application rates on grain filling characteristics and phosphorus absorption and utilization of dryland wheat after straw returning to the field were explored，in order to provide a theoretical basis for scientific application of phosphorus fertilizer to help high yield of dryland wheat. The wheat ‘Luohan 22’ was selected as the material，and the split plot experiment design was adopted in the experiment. The main area was the corn straw returning treatment，including no straw returning(S0) and full straw returning(S1)，and the sub area was the phosphorus application treatment，including 0 kg/hm²(P0)，75 kg/hm²(P1)，112.5 kg/hm²(P2)，150 kg/hm²(P3) and 187.5 kg/hm²(P4). The differences of wheat grain filling characteristics，dry matter accumulation and transportation，phosphorus absorption and utilization rate and yield formation of different treatments were analyzed. The results showed that:(1) the contribution rates of dry matter and phosphorus to grain after anthesis were significantly different under straw returning，but not different under different phosphorus application rates. Straw returning to the field and increasing phosphorus application both increased the dry matter and phosphorus accumulation of wheat organs，the dry matter and phosphorus assimilation after anthesis，and increased the number of wheat ears，the number of grains per ear and the 1000 grain weight，thus improved the wheat yield. Except for the 1000 grain weight，the above indicators all increased first and then decreased with the increase of phosphorus application rate，and reached the maximum value in P3 treatment. The spike number，grain number per spike and yield of P3 treatment were increased by 23.14%，9.81% and 26.87%， respectively，compared with P0 under S1 treatment，and increased by 20.82%，14.11% and 26.48%，respectively，compared with P0 under S0 treatment. The yield and spike number of S1 treatment increased by 3.78% and 4.74%，respectively，compared with S0 treatment at P3 level. The interaction of them had a significant effect on wheat yield，and reached the maximum in S1P3 treatment，which was 6928.66 kg/hm².(2) The maximum grain filling rate，the occurrence time of the maximum grain filling rate，the grain growth when the grain filling rate reached the maximum，the duration of grain filling，the average grain filling rate，the duration of increasing grain filling period and the duration of rapid increasing period were better in S1 treatment than those in S0 treatment. They increased first and then decreased with the increase of phosphorus application level，and reached the maximum value in P3 treatment. Both the straw returning and phosphorus application increased the maximum grain filling rate， maximum grain filling rate，average grain filling rate，and prolonged the grain filling period. Among them，S1P3 treatment was the most conducive to the optimization of winter wheat grain filling process，and then increased the 1000 grain weight. (3) Straw returning treatment promoted the absorption and utilization of phosphorus by wheat. The agronomic efficiency， partial productivity and absorption and utilization rate of phosphorus fertilizer increased by 1.26 kg/kg，2.7 kg/kg and 1.74%， respectively. With the increase of phosphorus application，the phosphorus absorption and utilization efficiency decreased. The interaction between them had a significant impact. To sum up，straw returning and 150 kg/hm² phosphate fertilize(r S1P3) can not only ensure the normal growth and yield of wheat，but also realize the efficient utilization of phosphorus.