The invention discloses a valve core assembly of a safety valve. The valve core assembly comprises a sliding seat, a thread sleeve arranged in the sliding seat and a valve pad which is arranged in the thread sleeve and matched with a liquid inlet connector of the safety valve, wherein the valve part is provided with a spherical groove. The valve core assembly is applied to the safety valve and can be used for controlling on-off of an oil line from a liquid inlet hole to a liquid discharge hole, high-flow overflowing can be realized when the valve core assembly is far away from the liquid inlet connector, the flow of the safety valve is greatly increased, axial displacement of the valve core assembly can be reduced through short-term fast overflowing, axial deformation of a reset spring can be reduced through reduction of the axial displacement of the valve core assembly, and pressure fluctuation can be reduced finally.