To study the impacts of formulations of DOC+CDPF on characteristics of particle emission from a Diesel Bus, a China-Ⅲ diesel bus with three different DOC+CDPF diesel engines were tested on heavy chassis dynamometer under China typical cities bus driving cycle (CCBC). The results showed that the mass concentration of PM was lower when precious medal load in DOC+CDPF catalyst was increased with the same ratio of proportion. The decrease of mass concentration of three recipes are 99.3%, 98.8% and 96.4% respectively, by an average of 98.2%. After using DOC+CDPF, particle size distribution of particulate matter changed from bimodal lognormal distribution to tri-modal lognormal distribution and the maximum peak point of corresponding particle size shifted with different catalyst formulations. At the same time, backpressure of engines emission increased slightly. In addition, while the precious metal load went higher, the pressure drop increment became less and the passive regeneration performance improved.