The influence of four kinds of amendments on physiological characteristics of cowpea and soil solution heavy metal concentrations at different growth stages were studied with pot experiments. The results showed that four amendments had no significant effect on pH value in soil solution because of soil buffer capacity. Peat and humic acid were more effective than palygorskite and diatomite in decreasing soil solution Zn and Cu concentrations, but no significant difference was found in Pb and Cd among four amendments. Peat, palygorskite, particularly humic acid, increased the activity of SOD and POD in cowpea leaves. The amendments except peat decreased the contents of MDA and proline in the leaves. The effects of amendments on physiological characteristics of cowpea were significantly weakened at the mature stage as a result of leaf senescence. Redundancy analysis indicated the inactivation effects of four amendments were in an order of humic acid＞peat＞palygorskite＞diatomite.