Abstract: The distributions of Cu, Pb, Zn, Cd and Cr in seawater and surface sediments of Daya Bay were investigated based on 2 cruises in August, 2014 and August, 2019. The results showed that the average contents of Cu, Pb, Zn, Cd and Cr in seawater were 0.9, 0.8, 4.2, 0.01 and 0.33 μg/L, respectively, in 2019. Compared to 2014, the contents of heavy metals in seawater of inner bay decreased significantly. The high contents of Cu, Pb, Zn and Cr were found in seawater close to the discharge outlet of the first petrochemical sewage pipeline in Daya Bay in 2014. However in 2019 affected by the discharge of the second petrochemical sewage pipeline, the high contents of Pb, Zn in seawater were mainly located at the mouth of Daya Bay. In 2019 the average contents of Cu, Pb, Zn, Cd and Cr in surface sediments were 14.3, 31.6, 74.4, 0.07 and 27.1 μg/g, respectively. Compared to 2014 the average content of Cd in the surface sediments decreased significantly, but the average contents of Cu, Pb, Zn increased slightly. The contents of heavy metals in the surface sediments in the southern sea area of the petrochemical industrial zone were high in both 2014 and 2019. The distribution of heavy metals in surface sediments were related to the hydrodynamics and land-based factors of Daya Bay. According to the results of 2019, the contents of Cu, Zn, Cd and Cr in the seawater were all met the class Ⅰ of national Sea Water Quality Standard (GB 3097-1997), wherea the content of Pb in 17.6% samples exceeded the class I of the standard. The contents of Cu, Pb, Zn, Cd and Cr in the surface sediments were all met the class Ⅰ of national standard Marine Sediment Quality (GB 18668-2002)