Abstract: In order to solve the problem of non-uniformity in the traditional pulse cleaning, the upper open scatter had been proposed to improve the internal flow field characteristics of the filter cartridge, so as to improve the cleaning efficiency. By numerical simulation method, the dynamic changes of pulse flow field and the dust cleaning pressure in the filter cartridge under different conditions were investigated, and the formation mechanism of the peak pressure of ash cleaning was explored. The results showed that the pulse-jet flow entered the filter cartridge in the form of pressure wave and transferred to the sidewall, and the pressure and radial velocity of the sidewall changed synchronously with time, and there was a direct connection between them. As a result of the diverting and guiding effect of the scatter on the jet flow, compared with no scatter case, the radial velocity of the upper part of the filter cartridge increased, thus dust cleaning pressure increased correspondingly, which the dust cleaning pressure increased from 484 Pa to 744 Pa, by 53.7%. On the contrary, the flow rate and axial velocity of the impulse injection in the middle and lower part of the filter cartridge would be reduced, the compression effect of the impulse airflow on the gas inside the filter cartridge would be reduced as well. The pressure in the middle and lower parts would be reduced respectively, and the pressure peak in the lower part decreased from 2175 Pa to 1468 Pa, by 32.5%. Therefore, adding a scatterer could obviously improve the uniformity of pulse ash cleaning and meet the requirements of ash cleaning.