Gasification rate of nascent Loy Yang char with H_2O/CO_2/O_2 atmospheres was studied in an atmospheric drop tube reactor. The effects of particle size and composition of gasifying agents on the yield of char and other products were investigated. The yield of char increases with increasing particle size in both N_2+steam and CO_2+steam atmospheres and the maximum differences of char yield are 37 and 44% on carbon mole basis, respectively. Compared with single steam gasification, the yield of H_2 decreased significantly and that of CO and soot increased in the co-gasification of CO_2 and steam. This suggests that CO_2 added inhibits char-H_2O reaction. In addition, small amount of O_2 added cannot influences char gasification, only just consuming combustible gas from the gasification process such as H_2 and reactive hydrocarbons.