In situ pressure-preserved coring (IPP-Coring) technology is considered one of the most efficient methods for assessing resources. However, seal failure caused by the rotation of pressure controllers greatly affects the success of pressure coring. In this paper, a novel spherical-cylindrical shell pressure controller was proposed. The finite element analysis model was used to analyze the stress distribution and deformation characteristics of the pressure controller at different rotation angles. The seal failure mechanism caused by the rotation of the pressure controller was discussed. The stress deviation rate was defined to quantitatively characterize the stress concentration. Based on the test equipment designed in this laboratory, the ultimate bearing strength of the pressure controller was tested. The results show that the rotation of the valve cover causes an increase in the deformation on its lower side. Furthermore, the specific sealing pressure in the weak zone is greatly reduced by a statistically significant amount, resulting in seal failure. When the valve cover rotates 5° around the major axis, the stress deviation rate is -92.6%. To prevent rotating failure of the pressure controller, it is necessary to control the rotation angle of the valve cover within 1° around the major axis. The results of this research can help engineers reduce failure-related accidents, provide countermeasures for pressure coring, and contribute to the exploration and evaluation of deep oil and gas resources.