Humic acid and fulvic acid were extracted from evergreen broadleaf forest surface layer soil of the Jingyun Mountains in China.The mechanism of humic acid(HA) and fulvic acid(FA) adsorption by Fe₂O₃、MnO₂ or Al₂O₃ solid sorbent in solution different in pH were studied.The results show that the adsorption increased with the organic carbon concentrations of HA and FA.The adsorption of HA,however,decreased with the rise in pH.When pH remained the same the percentage of HA in the adsorption decreased with the increase in organic carbon concentration of HA.At the same pH,the FA adsorption percentage curves all appeared to be a singlet,and the peaks moved towards low organic carbon concentrations of FA when pH rose.Langumuir equations were adapted to fit the adsorption.It indicated that the max adsorption quantities S_max and adsorption constants K of HA were more than those of FA,while the thermodynamic change in standard free energy of HAΔGm^o was less than that of FA at the same pH.The ΔGm^o of HA and FA were all less than zero,indicating the spontaneous adsorption reactions.