Abstract: The bay is the area where the interaction between the sea and land and human activities is most intense, and the content and distribution of heavy metals in sediments are strongly affected by human activities. In order to determine the pollution level and possible sources of heavy metals in Qinzhou Bay sediments, this study analyzed the concentrations and spatial distributions of Cu, Pb, Zn, Cd, Cr, Hg and As, analyzed quantitatively the pollution degree and ecological risk of heavy metals by geo-accumulation index (I_geo) and potential ecological risk index (PERI), and assessed quantitatively the possible sources of heavy metals by methods of self-organization mapping (SOM) and positive matrix factorization (PMF) model. Result showed that the average concentration of Zn was the highest and the average concentration of Hg was the lowest in the surface sediments of Qinzhou Bay. SOM and PMF modelling showed that heavy metals in surface sediments of Qinzhou Bay were mainly from natural sources, agricultural activities, industrial activities, and the relative contribution rates of the sources were 39.65%, 29.15% and 31.20%, respectively.