Abstract: Radionuclides in sediments of the Tianwan sea area were measured using the HPGe γspectrum method. Based on the data of sediments’ radionuclide content, the horizontal distribution of radionuclide content in surface sediments and the vertical distribution of radionuclide content in columnar sediments were analyzed, and the intrinsic correlation between the nuclides and the deposition rate in the near shore area of Tianwan were also discussed. The results showed that the surface sediments in the Tianwan sea area were basically silty clay and clayey silty sand, with an average median particle size of about 0.006 mm and an average clay content of about 45%, which are typical silty coastal sediments. Although the radioactive nuclide specific activities of ²¹⁰Pb, ²³⁸U, ²²⁸Ra, ⁴⁰K, ²²⁶Ra, ²²⁸Th, and ¹³⁷Cs in surface sediment varied greatly, the horizontal level of individual radionuclide was similar. The range of vertical specific activity of ²¹⁰Pb, ²²⁶Ra, ²³⁸U and ²²⁸Th was 32.6～48.8 Bq/kg, 17.6～33.3 Bq/kg, 15.1～40.8 Bq/kg and 40.3～86.9 Bq/kg, and each nuclide content changing with depth increase volatility rule was different. In the columnar sample, the vertical activity ratio of ²¹⁰Pb/²²⁶Ra was between 1.2 and 2.6, with the mean value of 1.5. Excess of ²¹⁰Pb was obvious in comparison with ²²⁶Ra and the excess was significantly related to the buried depth. Over the past 50 years, the average deposition rate near Tianwan was 2.3 cm/a, the deposition rate of column samples less than 60 cm was about 3.0 cm/a, and that of column samples greater than 60 cm was about 1.0 cm/a. deposition rate from 0 cm to 60 cm was relatively fast, which may be related to the influence of surrounding projects (Tianwan Cross-sea Bridge, drainage outlet, port expansion, etc.), and the deposition rate from 60 m to 100 cm was relatively slow and stable.