The invention discloses a gate valve for a cooling system on a ship. The gate valve comprises a handle (1), a valve body (2) and a gate (3). Bore type spiral depressions (4) are formed in the inner walls of a water inlet pipe cavity and a water outlet pipe cavity of the valve body (2), and the rotation direction of waterflow passing the water inlet pipe cavity is opposite to the rotation direction of waterflow passing the water outlet pipe cavity. The waterflow flows into an inner cavity of the valve body (2) in a rotary mode. In addition, due to the fact that the rotation direction of the waterflow passing the water inlet pipe cavity is opposite to the rotation direction of the waterflow passing the water outlet pipe cavity, more drastic agitation occurs in the middle, where a seal face is located, of the valve body (2), the calm conditions needed by implantation of shellfish creatures are damaged, implantation of the shellfish creatures in the inner cavity of the valve body (2) is prevented, and thus valve closing is smooth.