In this paper，the effect of nitrogen application management on translocation and partitioning of 14C assimilates and endogenous hormone levels of cotton leaf under mulched drip irrigation was studied using a cotton variety with early maturing and high yield.The total nitrogen amount applied is 270 kg·hm-2 .Three application methods are conducted，one is applying 80% of N before the flowering stage，second method is applying equivalent nitrogen during the three main N applying stages，and the last one is applying 50% of N before the flowering stage.The results showed that compared with the treatment of equivalent nitrogen application rate of 3 growth stages，the high nitrogen application rate in the early stage the content of indole acetic acid (IAA)，zeatin and its nucleoside (Z+ZR) of cotton leaf，and the contents of abscisic acid(ABA)，isopenteny ladenime and its nucleoside (iP+iPA) are all inproved during the late growth period of cotton,the 14C assimilates translocation to cotton boll，is promoted and increased the yield of seed cotton.Although for the high nitrogen application rate in the late stage the ABA content in leaves，the proportion of 14C assimilates partitioning to the boll，and boll weight were increased significantly，but the contents of IAA，Z+ZR of cotton leaf，resulted in rapid leaf aging were decreased and the yield of seed cotton decreased significantly.These results suggested that certain proportion of nitrogen fertilizer should be applied as basal fertilizer with mulched drip irrigation，and the proportion of additional nitrogen at late stage,should be appropriately increased which can affect the contents of ABA in leaves and accelerate the transportation of photosynthetic product to leaves，and increase boll weight.These measures for nitrogen management will fully exploit the water saving potential of mulched drip Irrigation.