The invention relates to a safe marine drilling rotary pressure-maintaining coring method, which comprises an outer pipe assembly and an inner pipe assembly mounted in the outer pipe assembly. A drillbit is arranged at the bottom end of the outer pipe assembly, the inner pipe assembly comprises an inner pipe assembly a and an inner pipe assembly b, the inner pipe assembly b is installed in the inner pipe assembly a and can move in the axial direction of the inner pipe assembly a, the inner pipe assembly a comprises a fishing spearhead, an elastic clamping mechanism, a piston pipe, a middle pipe short section, a sealing short section, an energy accumulator connecting pipe, a middle pipe and a pressure-maintaining ball valve turnover sealing mechanism which are sequentially connected from top to bottom, the inner pipe assembly b comprises a lifting device, a connecting mechanism, an elastic clamp hanging mechanism, a single-action mechanism, a conversion connector, an adjusting connector, an energy accumulator connecting pipe, a sealing mechanism, a temperature and pressure instrument connecting pipe, a rock core pipe connecting short section and a rock core pipe which are sequentially connected from top to bottom. The safe rotary pressure-maintaining sampling method can adapt to fourth-system sedimentary stratums and bedrock, and is more reliable in application.