Abstract: The effect of four inhibitors on soil nitrification and N₂O emission in Hainan was investigated in an indoor incubation experiment to screen appropriate nitrogen fertilizer inhibitors for soils in Hainan. Five treatments were set as CK (only urea), urea plus long-term compound fertilizer additive (8‰ Urea + NAM), urea plus dicyandiamide (DCD) (3.5% urea + DCD), urea plus 3, 4-dimethylpyrazole phosphate (DMPP) (1% urea + DMPP) and urea plus 2-chloro-6-trichloromethylpyridine (NMAX) (8‰ urea + NMAX). Soil pH, ammonium-nitrogen (NH₄⁺-N), nitrate and N₂O fluxes were determined in the incubation. Our results showed that compared with CK, four inhibitor addition treatments didn’t significantly affect soil pH, organic matter, total nitrogen and available potassium but significantly decreased soil available phosphorus. During the incubation, NH₄⁺-N concentration in NAM and NMAX treatments except DCD was at low level. However, nitrate concentration increased slowly showing obvious nitrification inhibiting effects. Compared with CK, the peak of N₂O flux was delayed and accumulative N₂O emissions were significantly decreased in four inhibitor added soils. However, there were no significant differences in inhibiting effect among four inhibitor addition treatments. Therefore, given the effects of nitrification inhibition and N₂O mitigation, nitrogen fertilizers added with NAM, DMPP and NMAX were considered to be suitably applied into rice paddy soil in Hainan.