Since 1945 ,thousands of nuclear experiments have been carried outin many countries .Those experiments , performed either in atmosphere or under seawater ,have posed a significant distribution to the radionuclide contami‐nation on the world oceans .The distribution and evolution process of radioactive materials in the ocean have to be studied based on the long‐term pollution characters ,w hich requires a marine radionuclides model to be established . Thus in this paper ,we have established a quasi‐global marine radionuclides model to study the transport ,distribu‐tion and evolution of the 137 Cs in the China seas ,resulting from the nuclear experiments since 1945 .The 137 Cs is in‐troduced into seawaters not only from the sub‐water experiments but also from the global fallout due to atmospher‐ic nuclear experiments .The simulated vertical and horizontal distribution of the 137 Cs agrees well with the observa‐tion .The decaying process of the 137 Cs is also presented in the simulation .The 137 Cs from nuclear experiments en‐tered in China seas since the 1940s .In the early 1960s ,the concentration of 137 Cs in China seas reached its maxi‐mum and then reduced gradually due to the decay of the 137 Cs and the dilution from sea waters .By 2011 ,the con‐centration of 137 Cs in China seas is less than 2 Bq/m3 and the concentration of 137 Cs is higher in the South China Sea than in the other seas .%1945年以来，世界各主要核国家进行了数千次核试验，这些核试验产生的绝大部分放射性物质通过多种途径进入海洋，对海洋环境造成放射性污染。本文建立了一个准全球海洋的放射性物质输运和扩散数值模式，通过数值模拟手段评估了历史核试验释放的放射性物质137 Cs对中国近海海洋环境的影响。本文借助前人工作评估了核试验释放137 Cs进入海洋的途径和总量；通过比较模拟结果与观测资料，表明本文建立的放射性物质模式能够较好地模拟出137 Cs在中国近海及其邻近海域的分布情况和随时间演变特征；模拟结果表明中国近海里的137 Cs浓度在20世纪50年代中期达到最大，其中吕宋海峡海域137 Cs浓度最高，达80.99 Bq／m3；进一步分析了2011年3月份日本福岛核事故前中国近海137 Cs浓度分布状况，2011年整个中国近海137 Cs浓度介于1.0～1.6 Bq／m3间，且其浓度垂向分布较均匀，相对封闭的南海浓度略高于其他海域。
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