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[Objective] Correlations between contents of heavy metals and sediments properties were analyzed. Speciation character and the bioavailability of heavy metals were discussed based on the rations secondary phase and primary phase(RSP) and potential ecological risk assessment. [Method]Taking the mangrove wetland sediments of Qinglan Harbor wetland in Hainan as the research object, speciation and contents of four heavy metals(Cu, Zn, Cd and Pb)in sediments of mangrove wetland were treated by BCR sequential extraction procedure. [Result] Between heavy metals it had different degrees of correlation and exhibited significantly positive correlation between Cd and Pb, suggesting that the pollution of Cd and Pb resulted from homologous pollutants. Cu and Cd were mainly in the acid soluble-extractable fraction;Pb was mainly in the reducible fraction;Zn was dominated by residual fraction;It showed that Cu, Cd and Zn in the sediments of the study area had serious potential hazards. There was significant correlation between the forms of Cd, Cu, Zn and PB of heavy metals in sediments. Contents of Cu and Cd existed as weak acid soluble fraction and oxide fraction exhibits significantly positive correlation with pH, indicating that sediments pH had a certain impact on chemical speciation of heavy metals. [Conclusion] These 4 kinds of heavy metals in the sediments have high bioactive state, and have strong biological activity, which are easy to be absorbed and used by plants. Cd, Cu, Zn and Pb have higher risk of release in the sediments of the research area, which should be paid enough attention. [ABSTRACT FROM AUTHOR]