The invention relates to a method for removing cationic dyes through two-stage adsorption by natural layered silicate nano particles and biological carbon. The method comprises the following steps: preparing nano silicate slurry, wherein the main component of the nano silicate slurry is natural layered silicate nano particles; throwing the nano silicate slurry into cationic dye wastewater; carrying out primary adsorption on cationic dyes by utilizing the natural layered silicate nano particles in the nano silicate slurry; after the primary adsorption is fully carried out, throwing biological carbon particles, and carrying out secondary adsorption on the natural layered silicate nano particles and the cationic dyes in the mixed solution; after the second adsorption is fully carried out, carrying out solid-liquid separation on the mixed solution to obtain a supernatant liquid. The outstanding feature of the method provided by the invention is as the follows that the natural layered silicate minerals and the biological carbon are both rich in sources and low in price. The method is simple in operation and easy to control, the adsorption and decolorizing effect is good, the adsorptioncapacity is more than 20 times of the adsorption capacity of the biological carbon, the cost performance is high, and the application is convenient.