In order to study the emission features of the light gasoline vehicle PN10 (particulate matter above 10 nm in diameter) and NH3 at different ambient temperatures (–10, 23, 30 ℃), with the four-wheel drive chassis test machine system, environmental chamber, PN particle counting device and the NH3 analyzer, A China VI certified light gasoline vehicle equipped with a three-way catalytic converter was tested using China light-duty vehicle test cycle, compare the emissions differences at different ambient temperatures and analyze PN10–23(particulate matter between 10 and 23 nm in diameter) emission levels. The results show that: PN10 and NH3 emissions are significantly affected by the ambient temperature, Compared with the normal temperature (23 ℃) emission, low temperature (–10 ℃) emissions are worse, and the emission factor of PN10 is more than 8 times, the emission factor of NH3 is nearly 1 times, PN10 and NH3 emission factors under high temperature (30 ℃) exceeded 23% and 44%, and the emissions of PN10 and NH3 were concentrated at low-speed stage; PN10–23 at each temperature accounted for about 30% of PN10 emissions, it is necessary to control 10 nm ~ 23 nm particulate matter.