Abstract: Transient working condition is the common working condition of non-road mobile machinery, which can better reflect the working condition of the whole vehicle.At present, NRTC is the only non-four-transient emission in China, but Southwest Research Institute has developed a new transient cycle LLAC（Low Load Application Cycle）.In this paper, the differences between NRTC cycle and LLAC cycle are studied through the diesel engine bench test, focusing on the analysis of the test results of NO_x and PM.The results show that the NRTC test results have better stability, and the LLAC cycle is more representative because of its low load, low exhaust temperature and frequent engine thermal management.