[en] Portability of radioactive aerosol monitor is required in some conditions, so a system and a method of low rate of flow sampling and quick survey have been designed in the article. The method of cumulative-sampling and cumulative-measurement has been chosen. The method of corrected energy discrimination and α/β ratio have been used for reducing the effect of radon progeny and thoron progeny. So α/β activity concentration can be monitored quickly in condition of low rate of flow sampling. The detection limit of the system is analysed, it is proved that the method has met some requirements of emergency response and been useful for design of portable radioactive aerosol monitor. (authors)