The structural evolution of rice husk char particles during steam gasification was studied. The chars were characterized by ultimate analysis, field emission scanning electron microscope (FESEM), N2 isothermal adsorption/desorption method and X-ray diffraction (XRD). The results indicate that with the development of gasification, the H/C atomic ratio always increases, but the O/C atomic ratio and oxygen content decrease firstly, then increase and decrease finally. As the conversion increases, the K, Ca, Na and Mg contents in rice husk chars first increase then decrease and the conversion values corresponding to their maximum peaks are different. The change trend of the micropore volume is similar to that of the surface area during gasification. As the degree of gasification reaction deepens, biomass chars become more ordered.