A new montmorillonite/humic acid complex preparation method in the alkaline environment was studied by experiment, and the complex effect on remediation of heavy metal pollution was verified. The best technological condition of the montmorillonite/humic acid complex preparation in alkaline environment was that the mass ratio between montmorillonite and humic acid was 100:3, the reaction solution was 0.01 mol/L sodium nitrate solution, the pH value of the reaction solution was 8.5, and the reaction time was 24 hours. The complex has better remediation effect on cadmium waste water. The cadmium adsorption capacity of the complex was 18.96 mg/g, and the pH value ranges of cadmium waste water suited for the complex was from 5 to 9.