Using 15N isotope tracertechnique，the effects of nitrogen fertilizer management on nitrogen uptake and utilizationof rice straw were revealed through pot simulationexperiments.Two treatments were set up in theexperiment:the applicationof base nitrogen fertilizer before transplanting(T1)and the application of base nitrogen fertilizer and straw at the sametime with adjusting C/Nratio(T2).The results of pot experiment showed that nitrogen use efficiency of T2 treatment wassignificantly higher than that of T1 treatment.Nitrogen uptake by rice from 15N straw(Ndf S)was significantly lower thanthat in soil and fertilizer(Ndf S+F).The comprehensive utilization rate of straw nitrogen for rice aboveground plants was 6.51%～7.99%，of which the utilization rate of straw nitrogen for stems and leaves was 1.40%～1.75%，and the utilization rate for panicles was 5.11%～5.25%.Under the condition of straw returning to thefield，the nitrogen absorption capacity of rice to straw cloud be significantly improved by applying base fertilizer and straw simultaneously.