Abstract: In order to investigate the emission characteristics of brake particulate matter under different deceleration braking conditions in the same cycle and under similar deceleration braking conditions in different cycles based on brake inertia test bench, some equivalent brake emission tests were conducted on WLTC cycle and US06 cycle in a sealed sampling compartment, and the emission of brake particulate matter with the particle size range of 10 nm～10 μm was measured. The test results show that the number of particles above 100 nm particle size emitted in the first four conditions of each cycle is poorly reproducible in multiple US06 cycle tests, and that an increase in the travel dynamics parameter (v·a) can result in poorer stability of the number of particles generated for all particle sizes. Particles above 100 nm size can contribute significantly to the brake particulate matter mass concentration, while the brake particulate matter number (PN) concentration emissions are more determined by 10～100 nm small particle size of particulate matter. The test results also show that the generation of particulate matter is closely related to the acceleration and speed of the working conditions, in the actual driving of the vehicle, higher driving speeds as well as larger brake acceleration can promote the generation of small-size particulate matter below 100 nm, while the generation of large-size particulate matter above 100 nm is mainly affected by the larger brake acceleration. And it can make the generation of both large and small particles less at the same time to keep the speed of the vehicle lower than 100 km/h and acceleration lower than 2 m/s². Comparing the particulate emissions data from the high speed and ultra-high speed segments between the US06 cycle and the WLTC cycle, the analysis process show the US06 cycle with more aggressive braking conditions tends to generate more large-size particles, whereas the WLTC cycle are more significant in terms of the generation of small-size particles in the ultra-high speed segments.