本文系统地研究了汽油机怠速工况下排气中ＨＣ和ＣＯ生成的基本规律，重点探讨了燃烧过程与ＨＣ、ＣＯ排放的内在关系。燃烧过程所考虑的因素主要有燃烧完善程度（用累积放热百分比表示），燃烧速率和着火时刻。试验发现燃烧速率对排放的影响较小。在空燃比较高（大于１３）的情况下，采用适当的废气再循环可显著降低排气中ＨＣ的生成量，这为改善现代汽油机怠速工况下的排放水平提供了有效的途径。 This paper systematically studies the basic rules of HC and CO generation in the exhaust of gasoline engine under idling condition and focuses on the inherent relationship between combustion process and HC and CO emissions. The factors considered in the combustion process are the degree of burnout (expressed as the cumulative heat release percentage), the rate of burning, and the moment of ignition. The experiment found that the combustion rate has little effect on the emissions. When the air-fuel ratio is high (more than 13), proper exhaust gas recirculation can significantly reduce the amount of HC generated in the exhaust gas, which provides an effective way to improve the emission level of modern gasoline engine under idling conditions.