Earthworm manure, the by-product obtained from the disposing of biowastes by earthworm breeding, is largely produced and employed as a feedstock for biochar preparation through pyrolysis. For repairing acidic soil or acidic electroplating effluent,biochar physicochemical properties would suffer from some changes like an acidic washing process, which hence affected its application functions. Pristine biochar(UBC)from pyrolysis of earthworm manure at 700°C and biochar treated by HCl(WBC) were comparatively investigated regarding their physicochemical properties, adsorption capability and adsorption mechanism of Cu~(2+) and Cd~(2+) from aqueous solution to explore the immobilization characteristics of biochar in acidic environment. After HCl treatment,the soluble ash content and phenolic-OH in the WBC sample was notably decreased against the increase of the carboxyl C_O, aromatic C_C and Si–O–Si, compared to that of UBC. All adsorption processes can be well described by Langmuir isotherm model. The calculated maximum adsorption capacity of Cu~(2+) and Cd~(2+) adsorption on UBC were 36.56 and 29.31 mg/g, respectively, which were higher than that of WBC(8.64 and 12.81 mg/g,respectively), indicating that HCl treatment significantly decreased biochar adsorption ability. Mechanism analysis revealed that alkali and alkaline earth metallic, salts(carbonates, phosphates and silicates), and surface functional groups were responsible for UBC adsorption, corresponding to ion exchange, precipitation and complexation,respectively. However, ion exchange made little contributions to WBC adsorption due to the great loss of soluble ash content. WBC adsorption was mainly attributed to the abundant exposure of silicates and surface functional groups(carboxyl C_O and aromatic C_C). Earthworm manure, the by-product obtained from the disposing of biowastes by earthworm breeding, is substantially produced and employed as a feedstock for biochar preparation through pyrolysis. For repairing acidic soil or acidic electroplating effluent, biochar physicochemical properties would suffer from some changes like an acidic washing process, which has affected its application functions. Pristine biochar (UBC) from pyrolysis of earthworm manure at 700 ° C and biochar treated by HCl (WBC) were comparatively investigated regarding their physicochemical properties, adsorption capability and adsorption mechanism of Cu ~ ( 2+) and Cd ~ (2+) from aqueous solution to explore the immobilization characteristics of biochar in acidic environment. After HCl treatment, the soluble ash content and phenolic-OH in the WBC sample was not likely decreased decreased against the increase of the carboxyl C_O , aromatic C_C and Si-O-Si, compared to that of UBC. All adsorption processes can be well described by Langmuir isotope The calculated maximum adsorption capacity of Cu 2+ and Cd 2+ adsorption on UBC were 36.56 and 29.31 mg / g, respectively, which were higher than that of WBC (8.64 and 12.81 mg / g, respectively), indicating that HCl treatment significantly decreased biochar adsorption ability. Mechanism analysis revealed that alkali and alkaline earth metallic, salts (carbonates, phosphates and silicates), and surface functional groups were responsible for UBC adsorption, corresponding to ion exchange, precipitation and complexation , respectively. However, ion exchange made little contributions to WBC adsorption due to the great loss of soluble ash content. WBC adsorption was to at great loss of soluble ash content.