To investigate the interaction among HA, Cu²⁺ and activated sludge, we researched the influence of adsorption time, pH, Cu²⁺ concentration and temperature on the adsorption of Cu²⁺ onto activated sludge in the presence of HA, respectively, and analyzed the adsorption mechanism from the aspects of thermodynamics, sludge characteristics and Fourier transform infrared spectroscopy(FTIR) before and after adsorption. The results show that the equilibrium time of the adsorption of Cu²⁺ onto activated sludge in the presence of HA is 90 min under the conditions of pH, the concentrations of activated sludge, Cu²⁺ and HA are 6, 2 g/L, 50 mg/L and 50 mg/L, respectively. When the adsorption equilibrium is reached, the adsorption capacity of Cu²⁺ is 45.98 mg/L and the adsorption rate is 91.96%. It's also found that HA can weaken the toxicity of Cu²⁺to activated sludge. The performance of activated sludge absorbing Cu²⁺ mainly depends on the hydrogen bond force and the dipole force, and the functional groups of polysaccharide lipid C-O and benzene ring C-H also play a major role in the process of adsorption.