The effects of different fertilization on rice growth, nitrogen use efficiency and loss were studied by in-situ and micro-area isotope experiments, and the mechanism was explored through the nitrogen transformation. The results show as follows:1) Compared with conventional surface application (CT), urea deep placement (DT) and urea deep application combined with organic addition (DT+M) significantly decrease ¹⁵N -NH₃ emission. The emission factors in DT and DT+M are 0.19% and 0.37%, which are 95.8% and 91.7% lower than that in CT, respectively. 2) Compared with CT, nitrogen deep application significantly increases the uptake of ¹⁵N from rice plant and root, and reduces the loss of ¹⁵N. DT+M has the lowest ¹⁵N loss among the different fertilizer treatments, which is 48.7% lower than that of CT. 3) Nitrogen deep application can enhance the fixation of soil NH₄⁺-N and increase nitrogen use efficiency. DT and DT+M increase nitrogen recovery efficiency by 69.8% and 57.1% compared with CT, respectively. In addition, DT also contributes to the increase of rice yield, but it is affected by environmental conditions. By contrast, DT+M gives a stable increase of rice yield.