Abstract: Based on the simple collision theory (SCT), the calculation method of biomass char gasification rate was developed and the combined parameters to characterize the pre-exponential factor were found. Furthermore, some experimental tests for six acid-washed biomass chars, such as the isothermal gasification and so on, were performed under CO₂ atmosphere, using a thermo-gravimetric analyzer (TGA) over the temperature ranges of 800-1000 ℃, respectively. Through the comparison of experimental data and modeling results, it is found that a good agreement is made and the developed model equations can provide an effective guidance to clarify the general gasification law of biomass chars.