Levels of indoor radon in air are studied by a continuous electrostatic radon monitor under normal living conditions to evaluate the influence of air conditioned ventilation on indoor air radon level. Results show that the indoor air radon concentrations are not much more than those without household conditioner living condition, although using household conditioner requires a sealed room which should lead to a higher radon level. Turning on air conditioner helps lower indoor radon level. Therefore, the total indoor air Rn levels are normal >ventilation>exhaust or indraft > exhaust plus indraft.