[en] To study the key measures of controlling the indoor radon hazards, the physical and chemical properties of radon, influence of ventilation on indoor radon level and contents of radon in building materials were discussed. It is less effective to only employ the remedial measures after construction and decoration of residence to reduce the indoor radon hazards. The key of controlling the indoor radon hazards is to decrease the sources of radon, especially selecting the zone of low radon content to build residence and using low radon content building materials. (authors)