Abstract: The distribution of bioavailability heavy metals (Cu,Pb,Zn,Cd,Cr) in Baotou section of the Yellow River was discussed,considering the pore water in sediments.The results showed that the heavy metals are endowed with different bioavailability in the sediment cores by depth,and the pollution of heavy metals has been accumulated in the sediment by rates.Further,the direct hazard of heavy metals is less than the indirect hazard in the sediment.