There is limited information about how environmental and soil variables affecting N2O emission in nitrification process. A fixed fraction of nitrification rate is often used to estimate N2O emission from soils in most of commonly used models. A laboratory incubation study was conducted to investigate the effect of soil temperature, moisture and ammonium concentration on nitrification-induced N2O emissions with an acidic sandy loam soil from south eastern Australia. The results showed the assumption of fixed fraction of nitrification rate converted into N2O is not valid. The impact of temperature on nitrification for this acidic soil follows Q10 function. Nitrification accelerates when soil WFPS increases, then reaches its peak at around 40% WFPS, and declines at 60% WFPS. By fitting with Michaelis-Menten equation, a maximum reaction velocity Vmax is derived as 6.7 µg N g-1 soil day-1 for this acidic sandy loam soil. The N2O emission fraction of nitrification rate declines as incubation temperature increases. It indicated that high temperature may reduce N2O leakage in nitrification process, which can be expressed by 1/(1+0.1*T). The ammonium-N concentration in the soil has a positive effect on N2O emission fraction of nitrification rate. The impact of soil WFPS on N2O emission fraction of nitrification rate is uncertain based on this experiment because N2O emission exponentially increases as WFPS increases from 40% to 60%, which indicated soil denitrification occurred at 60% WFPS which is probably due to the rewetting effect. The N2O emission fraction of nitrification rate ranged from 0.14 to 0.44% for this acidic sandy loam soil.