The invention discloses a closed hollow thin-wall plunger based on the SLM technology and a plunger pump. The plunger comprises a plunger main body and a countersunk bolt. The plunger main body is integrally formed by a plunger head portion, a connection portion and a plunger tail portion in sequence, the plunger head portion is a hollow sphere, and oil passing holes are formed in the hollow sphere; the plunger tail portion is a hollow cylinder, at least two evenly distributed spiral oil passing flow channels are arranged on the side wall of the hollow cylinder, and the spiral oil passing flow channels communicate with the oil passing holes in the connection portion; and a through hole is formed in the bottom of the hollow cylinder, and the countersunk bolt is rotatably connected to the through hole. According to the closed hollow thin-wall plunger based on SLM technology and the plunger pump, SLM rapid prototyping technology is applied to manufacture of a plunger and a plunger pump, so that a closed hollow thin-wall structure is designed, mass of the plunger is remarkably reduced, driving force, inertia force during movement and invalid volume are reduced, volume efficiency is improved, abrasion is relieved, usage performance of the plunger pump is remarkably improved, and the service life of the plunger pump is greatly prolonged.