The invention discloses a preparation method of heavy metal ion adsorbing materials and an application of the materials. According to the method, landfill leachate serves as raw materials, the landfill leachate and cellulose extracted from tobacco stems are grafted and copolymerized to prepare landfill leachate-tobacco stem cellulose compounds, the landfill leachate-tobacco stem cellulose compounds are gelatinized, regeneration, solvent exchange and vacuum drying are performed for the landfill leachate-tobacco stem cellulose compounds to prepare landfill leachate-tobacco stem cellulose aerogel, and prepared landfill leachate-tobacco stem cellulose aerogel materials are larger in hole diameter, high in porosity and stable in structure and have good sequestration, adsorption efficiency and adsorbing capacity for heavy metals in waste water. According to the preparation method, the landfill leachate-tobacco stems and the tobacco stems are low in cost and used, treatment cost of heavy metal ions can be reduced, resources can be greatly recycled, and environmental protection is facilitated.