Assessment of the pollution for the selected six heavy metals (Pb, Cu, Zn, Fe, Mn and Ni) in ten surface sediments sampled from Aha Lake in a dry season was made in the present investigation. Principal component analysis (PCA) was used to assess the sources of the heavy metals contamination and two components were extracted. Analysis of the lake characteristics and point source pollution revealed that the discharge of industrial effluent and coal mining wastewater were the possible sources of these heavy metals contamination. Based on the speciation characteristics of heavy metals in sediments, the method ratio of secondary phase to primary phase (RSP) was applied to evaluate the loadings and the bioavailability of these heavy metals. The RSP evaluation exhibited that Pb, Zn, Fe, Mn and Ni were mainly associated with Fe-Mn oxides besides residual phase, while Cu mainly existed in organic phase and residual phase. In summary, the potential risk posed to the lake caused by the heavy metals was high and descended in the order of Mn > Ni > Zn > Pb > Cu > Fe.