Abstract: An in-lab incubation experiment was conducted on applying biochar derived from wheat straw as a soil remediation amendment to study effect of the application, relative to rate, on forms of heavy metals in mining contaminated soil. Results show that after 150 days of incubation, biochar in the soil significantly increased soil pH and organic carbon content by 0.96%-2.62% and 9.1%-38.6%, respectively. With increasing biochar application rate, the content of acid-extractable Cu, Zn and Cd in the contaminated soil decreased by 7.0%-16.9%, 6.7%-11.8% and 5.3%-9.6%, respectively, while acid-extractable Pb remained almost unchanged. Biochar reduced the contents of reducible Cd and oxidizable Cu, Zn and Pb. The content of residual Cu, Zn, Cd and Pb increased obviously by 10.6%-46.8%, 5.9%-15.7%, 40.9%-191.9% and 1.5%-2.6%, respectively, in biochar amended treatments. Correlation analysis shows that soil pH values and organic carbon contents were significantly correlated with the contents of acid-extractable and residual heavy metals. In short, biochar can promote transformation of Cu, Zn, Cd and Pb in the contaminated soil from acid-extractable, reducible and oxidizable forms to residual form.