Abstract: A ventilation drug reduction device includes a main housing, a first rectification assembly, a second rectification assembly, and a flow isolating assembly; the main housing is composed of a first segment, a second segment, a third segment, and a fourth segment; the first rectification assembly is composed of first rectification plates; the second rectification assembly is composed of at least one second rectification plate; the flow isolating assembly is arranged in a cavity of the third segment; the fourth segment is configured as an outlet end. On the premise that the total construction cost is not obviously increased, high-pressure gas is rectified in a cavity of the main housing, so that the turbulivity of the high-pressure gas is reduced, and a stable insulating gas layer is formed at the bottom of a hull; in addition, the present invention further discloses a marine ventilation drug reduction system.