The invention discloses a sea water pump which comprises a pump body (1), a plunger type cylinder mounting rack (2) and an eccentric shaft (3), wherein a rear end cover (6) is provided with a liquid inlet and a liquid outlet; the eccentric shaft (3) is respectively fixed on a front end cover (5) and the rear end cover (6) by a bearing A (8) and a bearing B (9); one end of the eccentric shaft penetrates through the front end cover (5); the side wall of the plunger type cylinder mounting rack (2) is axially provided with two rows of plunger type cylinder mounting through holes which extend along the radial direction; a plunger pair is installed in each plunger type cylinder mounting through hole; the eccentric shaft (3) is provided with a bearing C (25) and a bearing D (26) cooperated with the two rows of plunger pairs; and the end part of the plunger is respectively abutted on the outer wall of the corresponding bearing. The sea water pump has the beneficial effect that the rated working pressure can achieve 45MPa, has the advantages of impact resistance, long service life, low noise, good self-adsorption capability and pollution-resistant capability and good sealing performance.