Abstract: In order to analyze the real-world emission characteristics of China Ⅵ hybrid electric vehicle under the altitude conditions of Beijing and Kunming, a hybrid electric vehicle with China Ⅵ emission standard was tested in Beijing and Kunming using Portable Emission Measurement Systems (PEMS). Based on the real-world emission test data, the emission characteristics of hybrid electric vehicle on urban, rural and highway roads were analyzed, and emissions of the tested vehicle were estimated using the moving window approach and arithmetic averaging method. The results demonstrated that: (1) The carbon monoxide (CO) and particle numbers (PN) emission rates on the three road types varied significantly, with peak values of 0.18 g/s and 3.75×10¹¹ partical per second, respectively. The fluctuation of CO emission mainly happened on highways, whereas PN emission mainly occurred on urban and rural roads. The fluctuation of nitrogen oxides (NO_x) emission mainly occurred on urban roads, and the maximum value was 0.016 g/s. (2) Due to effect of altitude and working conditions, CO emission factors of the tested vehicle in Kunming increased by 85% compared to Beijing, while the NO_x and PN emission factors decreased by 37% and 27%, respectively. (3) The pollutant emissions were calculated using the moving window approach and the arithmetic average method (representing the original vehicle emission results). The results show that the emissions calculated by the two algorithms in Beijing were very similar. However, in Kunming, the CO, NO_x and PN emission factors calculated using the arithmetic average method were 88%, 82% and 69% higher than those determined by the moving window approach, respectively. That is, at high altitudes (Kunming), the pollutant emissions of the tested vehicle using the moving window approach differ significantly from the original emissions of the tested vehicle. (4) The influence of working conditions on the CO₂ emission factors of the tested vehicle on urban and rural roads was greater than the effect of altitude, resulting in an increase in fuel consumption and a 17% rise in CO₂ emission factors in Kunming. The results also show that the CO and CO₂ emission factors in Kunming increased compared with Beijing, whereas NO_x and PN emission factors decreased.