Abstract: Pressure-preserved coring is an effective means to develop deep resources. However, due to the complexity of existing pressure-preserved technology, the average success rate of pressure-preserved coring is low. In response, a novel in situ magnetically controlled self-sealing pressure-preserved coring technology for deep reserves has been proposed and validated. This innovative technology distinguishes itself from conventional methods by employing noncontact forces to replace traditional pre-tensioning mechanisms, thereby enhancing the mechanical design of pressure-preserved coring equipment and significantly boosting the fault tolerance of the technology. Here, we report on the design, theoretical calculations, experimental validation, and industrial testing of this technology. Through theoretical and simulation calculations, the self-sealing composite magnetic field of the pressure controller was optimized. The initial pre-tensioning force of the optimal magnetic field was 13.05 N. The reliability of the magnetically controlled self-sealing pressure-preserved coring technology was verified using a self-developed self-sealing pressure performance testing platform, confirming the accuracy of the composite magnetic field calculation theory. Subsequently, a magnetically controlled self-triggering pressure-preserved coring device was designed. Field pressure-preserved coring was then conducted, preliminarily verifying the technology's effective self-sealing performance in industrial applications. Furthermore, the technology was analyzed and verified to be adaptable to complex reservoir environments with pressures up to 30 MPa, temperatures up to 80 °C, and pH values ranging from 1 to 14. These research results provide technical support for multidirectional pressure-preserved coring, thus paving a new technical route for deep energy exploration through coring.