Not many reports are available on researches on chemical fractions of heavy metals based on soil types.In this project，seven soil profiles，representing the seven sub-classes of soils typical of Hong Kong，were collected for analysis of chemical fractions of heavy metals (Cd，Cu，Pb and Zn) in these types of soils and their potential environmental risks，using three-step sequential extraction procedure laid down by the EC Reference Bureau (BCR).Potential environmental risk of the heavy metals in the soils was also addressed based on the relative contents of chemical fractions.Results indicate that besides some residual forms a substantial proportion of HOAc-soluble Cd，Pb and Zn was observed in the soils and varied with soil types.Copper fractions were dominated by residual and reducible phases (bound to organic matter and sulfide) in all the seven types of soils.Heavy metals in Orthic Gleysols and Udic Luvisols posed relatively higher potential risks to the biota and environment than in the others.Of the four metals lead was the highest in potential environmental risk.