In order to study the effects of urea，ammonium sulfate，and calcium nitrate applied before sowing，at budding period，and at initial flowering period with equal total nitrogen(N)application rate on the 15N recovery and the seed cotton yield，a pot trial using 15N trace technique with soil water levels beyond 60% of field capacity was carried out by a random block design，and the results would provide a theoretical basis for rational N fertilizer application of cotton. The results showed that the seed cotton yield with single application of urea and ammonium sulfate during the whole growth period of cotton was significantly higher than that of single application of calcium nitrate in the three fertilization periods，by 15.3% and 14.0%，respectively. The treatment“ammonium sulfate+ urea+ calcium nitrate”and“ammonium sulfate+ calcium nitrate+calcium nitrate” achieved the highest seed cotton yield，which was 10.5%，and 9.0% higher than that of the treatment“single application of urea in the three fertilization periods”.For N applied as base fertilizer，the order of 15N recovery rate of cotton plants(28.8% ～ 32.2%)was ammonium sulfate>urea>calcium nitrate.For N fertilizer applied at budding period，the order of 15N recovery rate of cotton plants(57.2% ～ 73.2%)was calcium nitrate>urea>ammonium sulfate. For N fertilizer applied at initial flowering period，the order of 15N recovery rate of cotton plants(71.8% ～ 82.7%)was calcium nitrate>ammonium sulfate>urea. Under the conditions of this experiment，ammonium sulfate applied as base fertilizer，urea or calcium nitrate applied at the budding period，and calcium nitrate applied at the initial flowering period increased the number of bolls per cotton and achieved higher seed cotton yield and N fertilizer recovery.