The real driving emissions of three lightduty vehicles that met the China fifth stage legislation of limits and measurement methods for emissions from lightduty vehicles were measured with the portable emission measurement system and the emissions data were processed using the moving average window method proposed by EU. The results show that the CO, NO_xand PN emissions in the cold start stage account for 69.9%, 23.1% and 68.8% of total emissions respectively. Taking the cold start emission into account, the results of CO, NO_x and PN emissions will increase by 19.5%, 4.3% and 16.3%. For the mild driving, the CO₂ emission is so low that too many windows cannot fall into the normal areas and hence the window cannot meet the normal requirements. Therefore the moving average window method proposed by the EU cannot be directly applied to evaluate the real driving emission of lightduty vehicle in China. With the increase of amended basic tolerance tol₁, the number of windows that fall into the normal area increases and the proportion of test that passes through the normal requirement also increases. However, the basic tolerance amendment will bring lots of calibration work.