Heavy metal pollution influences soil enzyme activities, subsequently soil quality or functions. Minimal information is available regarding the interactions of heavy metals and soil enzymes in variable charge soils. The objective of this study was to evaluate the response of key enzymes to Pb²⁺loading in two variable charge soils (RAR soil-clayey, mixed siliceous thermic typic Dystrochrept and REQ soil-clayey, kaolinitic thermic plinthite aquult). The activities of urease, dehydrogenase, acid phosphatase, sucrase, and FDA hydrolysis were measured in the soils treated with a wide range of Pb²⁺ concentrations (0 to 2400 mg kg^-1). The enzyme activities were generally lower in the RAR than the REQ soil. The activity of some enzymes was stimulated at low Pb2+ loadings (≤100 mg kg^-1), but was inhibited at high Pb²⁺ loadings (≥ 400 mg kg^-1). At the Pb²⁺ loadings > 400 mg kg^-1, urease activity and FDA hydrolysis were significantly inhibited. Acid phosphatase activity was stimulated at the Pb²⁺loadings ≤ 400 mg kg^-1 and inhibited at higher Pb²⁺ loadings in the RAR soil, but it was hardly affected by Pb²⁺ loadings in the REQ soils. There were no significant relationships between dehydrogenase and soil Pb²⁺ loadings in both RAR and REQ soils, nor between sucrase activity and soil Pb²⁺ loadings in the REQ soil. Growing celery and Chinese cabbage increased the activities of urease, acid phosphatase, and FDA hydrolysis, but had minimal effects on dehydrogenase and sucrase activities. These results indicate that the interactions of Pb with enzymes in variable charge soils are complicated, and urease and FDA hydrolysis appear to be sensitive to external Pb²⁺ loading and thus may serve as an indicator of Pb²⁺ contamination to variable charge soils.