Abstract：Microorganisms play an important role in the biogeochemical cycle of rare earth elements in weathering crust. In the previous metagenomic analyses of the microbial diversity in dolomite weathering crusts from central Guizhou， the phylum Actinobacteria was found to be a dominant taxon in rare earth-rich layers. In this study， the culturable actinomycetes from the layer of karstic weathering crust in Guizhou were isolated and identified， and their adsorption processes of lanthanum（Ⅲ） were also studied to elucidate the mechanism of microbial adsorption of rare earth elements. A total of 190 actinobacterial strains belonging to 19 genera were isolated from the karstic weathering crust in Guizhou by using selective isolation media. Genera Streptomyces， Nocardia and Micromonospora were the dominant groups of culturable actinomycetes， accounting for 62.11%， 12.63% and 11.05%， respectively. The maximum adsorption （dry weight， m/m） of the better rare earth tolerant strains Micromonospora aurantiaca KLBMP9018， Streptomyces mirabilis KLBMP8969 and Nocardia sp. KLBMP9014 in a 20 mL solution with La3+ concentration of 20 mg·L-1 were 24.32 mg·g-1， 25.37 mg·g-1 and 20.74 mg·g-1， respectively. Kinetic equations were fitted to the experimental data， showed that the process of La3+ biosorption by the three actinomycetes belonged to the pseudo second-order equation. The isothermal adsorption model was also plotted， and the Langmuir isothermal equilibrium model could better fit the adsorption process of La3+ by the three actinomycetes than the Freundlich isothermal equilibrium model， indicated that the cell surface is adsorbed as a single molecular layer. XPS results showed that the adsorbed La on the cell surface of the bacterium was in the trivalent state and no reduction reaction occurred. The FRIR analysis revealed to the amino， hydroxyl and carboxyl functional groups of the cell wall of the bacterium were involved in the adsorption process of La3+. The results validated that diverse actinomycetes inhabit the layer of dolomite weathering crust in central Guizhou， and their metabolic activities have an important role in the geochemical cycling process of La element.