The method of potted swamp cabbage was adopted to research the remediation effects of soybean straw biochar on soil contaminated by lead-zinc tailings. In the contaminated soil, the concentration of Cu, Zn, Pb and Cd was 50, 400, 1 119 and 3.4 mg/kg, respectively. The results showed that whether the soil contaminated by lead-zinc tailings or not, adding 3% biochar could significantly improve soil pH and inhibit the soil pH value reduction leaded by lead-zinc tailings pollution. Soybean straw biochar had different effects on effective state of heavy metals in soil contaminated by tailings and uncontaminated soil; compared with the uncontaminated soil, the passivation of 3% biochar could not offset the increase of bioavailability of heavy metal caused by lead-zinc tailings pollution. The pollution of lead-zinc tailings inhibited the growth of water spinach, and the application of 3% biochar could eliminate the inhibitory effect. Biochar significantly reduced heavy metal content of swamp cabbage roots in pollution soil, but in the aboveground part of swamp cabbage, biochar had different effects on different heavy metals; adding 3% biochar could prevent the migration of Cu, Zn, Pb and Cd from lead-zinc tailings contaminated soil to shoot of swamp cabbage. The effect of soybean straw biochar on the absorption of heavy metals in swamp cabbage was different in lead-zinc tailings contaminated soil and uncontaminated soil, there were interaction between elements, and dilution effect caused by biomass increase of swamp cabbage after adding biochar. Under the experimental conditions, evaluating from the biomass and heavy metal content in the edible parts of swamp cabbage, applying 3% soybean straw biochar could remedy pollution soil leaded by lead-zinc tailings.