Gasification is a process in which biomass is decomposed into small quantities of solid char and ash and large quantities of gaseous products in the presence of one or more fluidizing agents. In this paper, a lab scale fluidized bed gasifier was used to explore the effects of different kinds of calcined dolomites (CD-1, CD-2, and CD-3) on tar conversion and composition during air-steam gasification of biomass. Results showed that all dolomites have a good performance in terms of tar reduction but CD-2 is more reactive than two other dolomites with respect to tar destruction. When the temperature was lower than 850(?)C, conversion of tar was relatively low; however, with temperature increasing further (>850 C-?), tar conversion was greatly enhanced.