The multiferroic material Pb3Mn7O15 exhibits a high resistivity arising from the orbital electrons localized around the manganese ions, which hinders its potential applications. Previous studies indicated that the resistivity of Pb3Mn7O15 was influenced by its crystal structure and the distribution of Mn ions. Consequently, pressure-induced structural change are expected to represent a viable method for tuning the resistivity and other properties of this compound. In the present study, the pressure effect on the resistivity of Pb3Mn7O15 was investigated up to 42 GPa. Furthermore, the X-ray diffraction and Raman spectroscopy techniques, along with the density functional theory calculations were employed to study the crystal structure evolution of Pb3Mn7O15 under pressure. The results demonstrate an electronic semiconductor-metal phase transition in Pb3Mn7O15, accompanying an irreversible orthorhombic to monoclinic phase transition. Additionally, within the orthorhombic phase, an iso-structural phase transition is observed, originating from the magnetic moments collapse of manganese cations. This study provides compelling evidence that high-pressure processing can be employed to modulate the crystal structure and functional properties of multifunctional materials.