An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method(HPCD), is studied by an inductively coupled plasma optical emission spectrometry(ICP-OES) and an inductively coupled plasma mass spectrometry(ICP-MS). The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion, a high-pressure closed digestion method is optimized with less acid, complete digestion,less damage for digestion process. The marine geological samples are dissolved completely by a HF-HCl-HNO_3 system, the relative error(RE) for the analytical results are all less than 6.0%. The method detection limits are 2–40μg/g by the ICP-OES, and 6–80 ng/g by ICP-MS. The methods are used to determine the marine sediment reference materials(GBW07309, GBW07311, GBW07313), rock reference materials(GBW07103, GBW07104,GBW07105), and cobalt-rich crust reference materials(GBW07337, GBW07338, GBW07339), the obtained analytical results are in agreement with the certified values, and both of the relative standard deviation(RSD) and the relative error(RE) are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples. An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO 3 system with a high-pressure closed digestion method (HPCD), is studied by an inductively coupled plasma optical The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion , a high-pressure closed digestion method is optimized with less acid, complete digestion, less damage for digestion process. Th e marine geological samples are dissolved completely by a HF-HCl-HNO3 system, the relative error (RE) for the analytical results are all less than 6.0%. The method detection limits are 2-40 μg / g by the ICP-OES, and 6-80 ng / g by ICP-MS. The methods are used to determine the marine sediment reference materials (GBW07309, GBW07311, GBW07313), rock reference materials (GBW07103, GBW07104, GBW07105), and cobalt- rich crust reference materials (GBW07337 , GBW07338, GBW07339), the resulting analytical results are in agreement with the certified values, and both of the relative standard deviation (RSD) and the relative error (RE) are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples.