A hydraulic plunger pump variable control structure, comprising: a valve body having an oil inlet; a valve sleeve disposed in the valve body, and having a second oil chamber (Pd) communicated with the oil inlet and a third oil chamber (Pp) suitable to be communicated with a variable piston pump; a main valve core movably disposed in and through the valve sleeve, and having a first end provided with a spring loaded assembly, and a second end provided with a pilot valve core, the spring loaded assembly being configured to provide a reverse preloading force; a main valve sleeve fitted over the pilot valve core, and provided with a first oil chamber (Pc), the first oil chamber (Pc) being able to make oil at the oil inlet flow to the pilot valve core, such that the pilot valve core can move under the action of oil pressure and the preloading force of the spring loaded assembly, to drive the main valve core to move in a first direction, thereby realizing communication and dis-communication between the second oil chamber (Pd) and the third oil chamber (Pp) through controlling relative displacement between the main valve core and the valve sleeve; a feedback rod having a first end connected with the valve sleeve and a second end capable of connecting the variable piston pump, such that during movement of the variable piston pump, the feedback rod drives the valve sleeve to move in a second direction opposite the first direction, wherein the valve body also has an external oil receiving port (Pi), and hydraulic oil at the external oil receiving port (Pi) acts on the pilot valve core to drive the pilot valve core to move; the pilot valve core comprises three tube-body structures, and adjacent two tube-body structures have an area difference therebetween to form a valve-core acting surface; and the valve-core acting surface extends into an annular shape along a circumferential direction of the pilot valve core, and respective diameters of the three tube-body structures are d2, d and d1 sequentially, in which d1 > d > d2, characterized in that the hydraulic oil entering from the external oil receiving port (Pi) is suitable to act on an end face with an area of π*d2^2/4 of the tube-body structure with the diameter d2. a valve body having an oil inlet; a valve sleeve disposed in the valve body, and having a second oil chamber (Pd) communicated with the oil inlet and a third oil chamber (Pp) suitable to be communicated with a variable piston pump; a main valve core movably disposed in and through the valve sleeve, and having a first end provided with a spring loaded assembly, and a second end provided with a pilot valve core, the spring loaded assembly being configured to provide a reverse preloading force; a main valve sleeve fitted over the pilot valve core, and provided with a first oil chamber (Pc), the first oil chamber (Pc) being able to make oil at the oil inlet flow to the pilot valve core, such that the pilot valve core can move under the action of oil pressure and the preloading force of the spring loaded assembly, to drive the main valve core to move in a first direction, thereby realizing communication and dis-communication between the second oil chamber (Pd) and the third oil chamber (Pp) through controlling relative displacement between the main valve core and the valve sleeve; a feedback rod having a first end connected with the valve sleeve and a second end capable of connecting the variable piston pump, such that during movement of the variable piston pump, the feedback rod drives the valve sleeve to move in a second direction opposite the first direction, wherein the valve body also has an external oil receiving port (Pi), and hydraulic oil at the external oil receiving port (Pi) acts on the pilot valve core to drive the pilot valve core to move; the pilot valve core comprises three tube-body structures, and adjacent two tube-body structures have an area difference therebetween to form a valve-core acting surface; and the valve-core acting surface extends into an annular shape along a circumferential direction of the pilot valve core, and respective diameters of the three tube-body structures are d2, d and d1 sequentially, in which d1 > d > d2, characterized in that the hydraulic oil entering from the external oil receiving port (Pi) is suitable to act on an end face with an area of π*d2^2/4 of the tube-body structure with the diameter d2.