Abstract: To evaluate the consistency of ESC (European steady cycle) and ETC (European transient cycle) model with bus driving cycle and to compare the emission discrepancy between legislation limits and real-time measurement, the bus driving cycle survey and real-time emission test have been conducted. The statistical characteristic of bus driving cycle was derived from the clustering analysis of driving cycle survey. Four buses which have the same characteristic were chosen to conduct real-time measurement using SEMTECH portable gaseous pollutant analyzer. The results indicate that there have great differences between the bus real-time driving cycle and regulations of ESC stable model and ETC transient model. The CO and NO_<em>x emission of the four buses exceed the limits frequently though the engines of the buses did pass the ESC and ETC legislation. In other words, the existing models can not control buses emission effectively. It is necessary to develop a special model for approving bus type on test bench or use portable emission test equipments as a supplement measurement.