The invention discloses preparation and use methods of a helianthus stem and leaf adsorbing material for heavy metals. The preparation method comprises the steps of: drying helianthus stem and leaves, crushing to 20-40 meshes, soaking in 0.01-1 mol/L diluted sodium hydroxide solution for 24-36 hours, filtering, washing with deionized water to be neutral, drying to constant weight and crushing to 40-80 meshes to obtain the product. The use method comprises the steps of: directly using the adsorbing material to the required places or devices by filter tank layered paving, filtering column holding, filtering sphere holding, container filling or bulk loading. According to the invention, the process is simple and convenient and low in cost; and after being used, the product is completely biodegraded and has no pollution to environment. The adsorbing material can be widely applied to adsorption and separation of heavy metals and radionuclides in wastewater in mining, mining and metallurgy, chemical industry, electroplating, machine, medicine, national defense and war industry and other industries.