Abstract: The mercury contents in 20 surface sediments and 2 flathead fish (Platycephalus indicus) samples collected from the offshore waters around Leizhou Peninsula were analyzed and compared. The results showed that mercury contents of different sediments ranged from 0.005×10^-6 to 0.359×10^-6 with an average of 0.081×10^-6. As a whole, the mercury contents in the sediments from the eastern offshore waters of Leizhou Peninsula were higher than those of southern and western offshore waters. Mercury contents in three fish organs, gill, muscle and liver, were in range of 0.032×10^-6-0.034×10^-6, 0.065×10^-6-0.080×10^-6 and 0.228×10^-6-0.270×10^-6, respectively, and the mercury contents were in order of liver > muscle > gill. The results of P_i index assessment indicated that the fish was polluted by mercury slightly. Moreover there is an ecological risk of mercury pollution in the eastern offshore waters of Leizhou Peninsula, while the southern and western waters were not threatened by mercury pollution.