The number and mass concentrations of aerosol particulate size ranging from 10 to 10000 nm in indoor and outdoor air was measured using wide range particle spectrometer (Model 1000XP WPS) produced by MSP Corporation , and the nanoparticle size (10 - 500 nm) in various room conditions was highlighted. It was found that the ultrafine particles (10~500 nm) has more contribution to the total number concentration, and the fine particles (500 nm~1000 nm) has more contribution to the total mass concentration. The results also showed that the mass concentration of indoor fine particulates was lower than that of outdoor and the nanoparticles are dominant in indoor atmosphere. The number or mass concentrations of nanoparticle increased greatly when smoking happens.