The invention discloses a method for obtaining the total organic carbon content of a marine underground medium. The method includes the following steps that: Occam inversion calculation is performed on acquired electromagnetic field data in an exploration region, so that the resistivity of the exploration region can be obtained; after the resistivity information is converted into complex resistivity through a Cole-Cole model, Occam inversion calculation is performed on the complex resistivity, so that polarization rate can be obtained; and the total organic carbon content information of the exploration region is obtained through utilizing the positive correlation between the polarization rate and the total organic carbon content. Compared with the prior art, and with the method of the invention adopted, the distribution rule of the organic carbon content in a plane can be obtained without well drilling required, and the method is of great significance for predicting gas bearing formations, guiding offshore oil and gas exploration and improving the success rate of misering and development.