Effects of pH and acetate concentration on the adsorption of acid phosphatase and BSA by soil colloid and clay minerals (SCCM) were studied. The results showed that the pH for the maximum adsorption of enzyme and BSA were between the IEP of protein and the PZC of SCCM. In the acetate systems, the amount of enzyme and BSA adsorbed by SCCM increased in the order goethite >> yellow brown soil> latosol > kaolinite> δ -MnO₂. Remarkable influences of acetate concentrat ion on the amount of adsorption and the binding energy of enzyme and BSA were observed. With the increase in acetic acid concentration from 0 to 200 mmol L^-1 in the system, acetic acid exhibited an initial enhancing effect followed by an inhibitingaction on the adsorption of enzyme and BSA on SCCM. The changes in binding energy (K value) for enzyme and BSA by SCCM were contrary to the trend for maximum adsorption. The possible mechanisms for the influence of acetate on the adsorption of enzyme and BSA by SCCM were discussed.