An objective of the present invention is to provide a large-flow plunger pump to solve the problems in the prior art and to improve the performance and the service life of large-flow plunger pumps.To make the objectives, features and advantages of the present invention more obvious and comprehensible, the present invention will be further described below in detail by specific implementations with reference to the accompanying drawings.Embodiment 1As shown in Figs. 1, 2, 3 and 5, the structure and principle of a large-flow plunger pump of the present invention will be described in this embodiment.This embodiment provides a large-flow plunger pump, comprising a box 16, a crank-link mechanism 7, a crosshead 17, a plurality of plungers 2-7, a suction valve and a discharge valve. The crank-link mechanism 7 drives the plurality of plunger 2-7 to do reciprocating motion. A crosshead 17 guide hole comprises a detachable upper crosshead guide 1 and a lower crosshead guide 1-3 located on an inner surface of the box. The detachable upper crosshead guide 1 is connected to the lower crosshead guide 1-3 via positioning pins 1-1 and fixing bolts 1-2. On each of the plurality of plungers 2-7, a plunger packing lubrication system 2 is provided, which supplies lubrication oil to each of the plurality of plungers by a multi-point lubrication oil pump via a check valve 2-10 and a pressure sensor 2-11, and a high-pressure lubrication oil pump of the multi-point lubrication oil pump supplies lubrication oil to a plurality of plunger packing sets separately via a plurality of lubrication oil pipes. Both the suction valve and the discharge valve are damping valves 3, each of the damping valves 3 comprises a damping ring 3-3 which is provided between a valve plate 3-1 integrally vulcanized with the damping ring 3-3 and a valve seat 3-2, and a volume cavity Q which is connected to a valve chamber via pores K on the valve plate 3-1 is formed within the damping ring 3-3. The damping ring 3-3 has a reinforcing plate T on its bottom. On the top of the detachable upper crosshead guide 1, an upper cover plate 14 is provided; and a pull rod assembly 5 is provided between the detachable upper crosshead guide 1 and the upper cover plate 14.