The response surface method was used to study the factors affecting the removal of As(III) by iron-modified vermiculite-humic acid composite adsorbent (adsorption time, adsorption dose, pH, proportion of humic acid content in adsorbent, As(III) The initial concentration), the quadratic polynomial model of the removal factor and the optimal adsorption conditions were obtained, and the adsorption kinetics and thermodynamics of the adsorption behavior were discussed. The results showed that all the five factors had significant effects on the adsorption of As(III) by the composite adsorbent. The optimal conditions for adsorption were: time 235 min, adsorbent dose 8.48 g.L^-1, pH 6.4, humic acid ratio 20%, As (III) initial concentration of 11mg.L^-1, the maximum removal rate of 96.06%; Langmuir, Freundlich equation fitting showed that Langmuir fitting results were the best, the maximum adsorption capacity was 3.94mg.g^-1 (313K); The adsorption kinetics study shows that the adsorption process conforms to the quasi-secondary kinetic model. The calculation of the thermodynamic functionsDG、DH、DS of the adsorption process shows that the adsorption process is a spontaneous endothermic process, and the adsorption process increases the system"s Chaos.