Air quality in the storage environment is critical to protection of cultural relics. Because of inadequate protection some of cultural relics that have been stored for a long time are partly stained some have color changes and some have warped lacquer and polychrome layers. In order to avoid this damage to the relics, it is necessary to study the storage environment, so as to develop a scientifically based way to control it. From Jan 30th to Mar 3rd (winter), Jul 28th to Aug 22nd (summer), 2008, a series of indoor air sample were collected. The microclimate monitoring was conducted in pottery storage room of the Emperor Qinshihuang's Mausoleum Site Museum to determine the concentrations of airborne water-soluble ions particulate matter (PM2.5) and SO2 and NH3 gases in the air. The results show that the average PM2.5 mass and water soluble ion concentration are higher in winter than in summer, whereas these values are higher outdoors than indoors. However, there are some exceptions, the indoor concentrations of Cl- and CO are higher than outdoor concentrations in summer. Also, due to the temperature, the concentration of NH3 is higher in summer than in winter; and in summer, the indoor NH3 concentration is higher than it is outdoors. Thus the air pollution and microclimate show obvious seasonal variations. The concentrations of some pollutants are higher than normal and may have some impact on the cultural relics in the storage room that needs to be addressed.