Back pressure and PN filter efficiency are key indicators of DPF carrier and CDPF catalyst. Research was conducted based on blank carrier pore size and coating load. The results showed that the pore size was the key that influenced the DPF/CDPF back pressure and PN emission. The smaller the pore size, the greater the back pressure, and the higher the PN filter efficiency. Decreasing the pore size could improve the PN filter efficiency, but the increase rate of back pressure is difficult to control. After applying the coating, the distribution of pore size was effectively controlled and shifted towards small pore size, which achieved the simultaneous improvement of PN filter efficiency and effective control of back pressure increase rate. Based on the collaboration of carrier and coating technology, DPF carrier with a median pore size of 11.5 μm was selected, the coating of 3.5 μm particle size and 15 g/L soot load was applied, and the back pressure increase rate and PN emission were 8.88% and 9.34×10¹⁰ #/（kW·h） respectively after coating. Accordingly, the requirements of China Ⅵ emission regulation were met and the efficient PN filtering and low back pressure increase rate were achieved.