Abstract: Oil shale ash, an inorganic byproduct of burning oil shale and retored shale, has a potential use, such as building material,chemical filling material,adsorbent, etc. To obtain oil shale ash with higher porosity, the pore structure of oil shale ash produced by the combustion of oil shale was measured by using the N2 isothermal adsorption/desorption method.As a result of comparison between oil shale ash samples prepared under different combustion conditions in terms of pore structure, the oil shale ash, formed under both higher heating rate and particle final temperature lower than the melting point of oil shale ash, had a larger pore volume and specific surface area and could be utilized in industries.