Alkaline Ca-bentonite (ACB) was investigated to remove Methylene blue (MB) and Congo red (CR) from aqueous solution as a function of adsorbent dosage, contact time and temperature, initial pH and salt. The adsorption isotherms and adsorption kinetics of the two dyes on ACB were also studied. The main results are as follows: MB and CR removal by ACB increased with the increase of adsorbent dosage. Under experimental conditions, the optimum adsorbent dosage for 50 mg/L MB and 100 mg/L CR were 1.0 g/L and 2.0 g/L, respectively; The elevated adsorption temperature contributed to accelerate the adsorption rate of MB and CR on ACB, but it had little impact on the final decolorizing rate of MB and CR；For 50 mg/L MB and 100 mg/L CR with the optimum adsorbent dosage of ACB, the adsorption equilibrium time were 60 min and 120 min, respectively. The decolorizing rate of MB by ACB remained about 99% when the initial pH increased from 3 to 12, and that of CR by ACB remained about 90% within the optimum pH range 3-7.The addition of NaCl had little effect on MB adsorption but suppressed CR adsorption obviously. MB adsorption on ACB followed both the Langmuir model and the Freundlich model, but CR adsorption on ACB followed the Langmuir model better.The adsorption process of MB and CR can be better described by the pseudo-second-order model than the pseudo-first-order model. The intraparticle diffusion model studies indicated there was pore-filling by diffusing during the adsorption process.