By the combination of polyaspartyl polymer and chitosan, a kind of novel environmentally friendly biomimetic blend material with peptide−polysaccharide-resembling structure was synthesized for heavy-metal removal. The resulting blend possesses diversified functional groups and was further modified by introducing a mercapto group through esterification between thioglycollic acid and hydroxyl group in the structure of chitosan. The polyaspartyl polymer−chitosan blend with 2.2 wt % mercapto group content improves the adsorption of organic compounds of mercury and arsenic. The blend exhibits a lower swelling behavior in the presence of water and is verified to have a potential biodegradability by elemental analysis and infrared spectrum (FT-IR).