Through the wheat potting experiment under different nitrogen (15N)combined with phosphorus and application methods in calcareous fluvo-aquic soil，the nitrogen uptake and utilization of wheat and index of nitrogen fertilizer use efficiency were investigated.The mixed application was urea (N1)and ammonium sulfate (N2)combined with calcium dihydrogen phosphate (P1)and diammonium hydrogen phosphate (P2).The three different fertilizer methods included:in the entire soil pot(A)；strip application with a vertical distance of 5 cm from the soil surface and a horizontal distance of 0 cm from the root system of wheat(B)； and strip application with a vertical distance of 5 cm from the soil surface and a horizontal distance of 12 cm from the root system of wheat(C).The results showed that (1)The 15N of wheat grain derived from application method B was significantly higher than A with P1N1，P2N1 and P2N2 fertilizer combination，which was the highest with a value of 0.37 g·pot-1 for the application method B of P1N2.The strip application of nitrogen fertilizer at a certain soil depth was better than the mixed application in the whole soil pot.(2)The nitrogen fertilizer use efficiency with 15N trace method of application method B was significantly higher than A under P1N2，P2N1 and P2N2 with the same fertilizer combination and different application methods.It was better to choose nitrogen fertilizer use efficiency with 15N trace method in soil with high soil fertility.These results provided an important reference for reasonably applying nitrogen fertilizer and scientifically evaluating nitrogen fertilizer use efficiency of wheat in fluvo-aquic soil.