Yield and water effect, accumulation and distribution of dry matter and grain filling of spring wheat after flowering under supplementary irrigation with catchment rainfall were studied at the trial station of Dingxi county in semiarid area of central Gansu. The results of experiment showed that there were it has improved the level of yield ,WUE and IWUE of spring wheat under supplementary irrigation(SI),and there were compensation or over-compensation effect for dry land farming crop. There were highest WUE at jointing stage, and highest IWUE at jointing booting stage. Accumulation and distribution dynamics of dry matter of leafs, stems and sheathes differed from those of spikes and all plants. Accumulation, output per day and RGR of spring wheat under SI were higher than that of CK. Moreover grain filling continuance and average grain filling of wheat were improved under SI.