重型车辆的整车排放测试是国Ⅵ排放法规的重要测试项目之一。以满足国Ⅵ排放法规的重型天然气发动机为研究对象，分别进行发动机台架WHTC循环和整车实际道路排放PEMS测试，并将发动机运行工况、排放测试结果进行对比分析。研究发现，两种排放测试方法发动机运行工况有一定的相似性，但是WHTC循环测试时发动机排温上升较快且过量空气系数波动较小，三元催化器的催化转化效率较高。两种测试方法下污染物排放均满足国Ⅵ排放限值，但是由于发动机运行工况及外界条件的变化，两者之间的排放存在着一定的差异，发动机台架WHTC循环排放值较低，NO_x的比排放值相差16.41%，CO排放相差20.2%,THC排放相差15.8%。发动机在进行开发标定时需要兼顾两种工况，对排放留出更宽裕度。

The vehicle emission test of heavy vehicle is one of the important test items of China Ⅵ emission regulation. Taking China Ⅵ heavyduty natural gas engine as the research object, the engine bench WHTC cycle and the PEMS real world emission test were respectively carried out, and the engine operating conditions and emission test results were compared and analyzed. The results show that engine operating conditions of the two methods are similar to some extent, but engine exhaust temperature of WHTC has a quick rise and the excess air coefficient has a little fluctuation so that threeway catalytic converter has high catalytic conversion efficiency. The pollutant emission of both methods can meet the limit requirements of China Ⅵ emission,  but a certain difference between them exists due to the change of engine operating conditions and external conditions. The bench WHTC cycle emission is lower and the differences of NO_x, CO and THC specific emission are 16.41%, 20.2% and 15.8% respectively. Accordingly, the development and calibration of engine needs to take into account the two operating conditions to leave more allowance for emissions.