In experimental conditions, the tested soil treated with Cd, Cu and Zn, the microbial biomass carbon and enzyme activities affected by simulated acid rain were studied. The results showed that microbial biomass carbon and enzyme activities in soil were decreased significantly. The activity of dehydrogenase was almost lost, and the activities of urease, acid phosphomonoesterase, total phosphatase and polyphenol oxidase were decreased significantly, too. With increasing contents of heavy metals, the microbial biomass carbon and enzyme activities decreased more deeply and correlatively with the c...