The study aimed to effectively prevent and control the loss risk of ammonia(NH₃)volatilization and improve the utilization efficiency of nitrogen(N)fertilizer in rice. Organic fertilizer N was set to replace chemical fertilizer N with six different replacement ratios:0%(ON0)，10%(ON0.1)，20%(ON0.2)，30%(ON0.3)，50%(ON0.5)，80%(ON0.8) and a control treatment(no N，CK). Field experiment was conducted using the closed chamber intermittent ventilation method to study the effects of different organic N replacement ratio on the seasonal variation of soil NH₃ volatilization rate and its loss characteristic，and N fertilizer utilization efficiency in double-cropping rice field. The results showed that N fertilizer absorption and utilization ratio，N fertilizer agronomic utilization ratio，N fertilizer partial productivity and N harvest index of rice first increased and then decreased with the increase of organic fertilizer N substitution ratio，and the N fertilizer utilization ratio of early rice was significantly higher than that of ON0 treatment. The peak value of NH₃ volatilization in early-and late- rice fields occurred at 2 to 5 and 1 to 3 d after fertilization，respectively. The highest total volatilization loss(rate)of NH₃ was observed under ON0 treatment，which was N 76.18 kg·hm-2(22.38%)，during the growing season of double cropping rice. The total volatilization loss(rate)of NH₃ in organic N replacement treatments was N 42.26-68.13 kg·hm-2(12.81%-20.65%)，which was significantly negatively correlated with the N replacement ratio of organic fertilizer. The NH₃ volatilization per unit yield of double cropping rice in organic N replacement treatments was 0.74-2.10 kg·t-1 lower than that in ON0 treatment. The emission reduction effect of organic fertilizer N replaced by 20%-80% treatments in early rice season and by 30%-80% treatments in late rice season reached a significant level. Correlation analysis showed that the total amount of NH₃ volatilization had a significant positive correlation with the average NH4+-N concentration of surface water，but had no significant correlation with the average NO^3--N concentration and pH. In general，replacing 20%-30% of fertilizer nitrogen with organic fertilizer N could effectively reduce NH₃ volatilization in double-cropping rice fields，reduce the risk of N loss，simultaneously promote nutrient absorption，and improve N fertilizer utilization efficiency in rice fields.