Abstract: In order to understand the current status of NH₃ emissions from light-duty gasoline vehicles, NH₃ emissions from a China 6 light-duty gasoline vehicle equipped with a three-way catalytic converter (TWC) were tested under three test cycles, respectively, including worldwide light-duty test cycle (WLTC), China light-duty vehicle test cycle (CLTC), and federal test procedure (FTP-75) operating cycles. Instantaneous NH₃ emission characteristics and the impact of different ambient temperatures (−7, 0, 23, 35 ℃) to NH₃ emissions under WLTC cycle were analyzed, moreover, the NH₃ emission factors under three test cycles were also compared. The results showed that no NH₃ emission was observed during the first 50 s of the cold start under WLTC cycle. NH₃ emissions were concentrated primarily in the low speed and medium speed phase (first 900 s), while few NH₃ emissions occurred in the high speed and ultra-high speed phase. Light-duty gasoline vehicle emitted more NH₃ in the acceleration range at low speeds (v<40 km/h). The NH₃ emission factors decreased with the increasing ambient temperature, but increased at 35 °C slightly. The NH₃ emission factor of low-speed phase at −7 °C was 1.4 to 2.2 times greater than at 0, 23 and 35 °C. Under WLTC cycle, the NH₃ emission factors of the vehicle at various test ambient temperatures were in the order of low speed phase > medium speed phase > high speed phase > ultra-high speed phase. The NH₃ emission factors of the light-duty gasoline vehicle differed significantly under the three cycles, and the WLTC cycle showed the smallest emission factor. The results indicated that NH₃ emissions from light-duty gasoline vehicle were relatively high at low temperatures (−7 °C).