The estimation of internal radiation dose is very important in radiation protection. It is necessary to provide an method to assess the effects of internal exposure dose on the local residents due to the absorption of this marine biota in Daya Bay. Base on the numerical simulation of tide pollution diffusing, a internal exposure dose rate assessing model is providedto estimate the radiation dose rate by the absorption of marine biota in Daya Bay. The result showed that internal radiation dose for each person is between 10^-6~10^-9Sv per year. and it was less than the natural background radiometric radiation level.