Deck drainage system based on oil tanker

Disclosed is a deck drainage system based on an oil tanker. The deck drainage system comprises a drainage port which is formed in a deck, a drainage pipe which is arranged below the drainage port anda detachably-connected filtering hopper; annular sealing rubber strips are circumferentially distributed at the periphery of the bottom of the drainage port; two positioning sealing rings are arrangedon the inner side wall of the top of the drainage pipe, and annular grooves are formed in the middles of the inner sides of the positioning sealing rings; the outer side wall of the top of the filtering hopper is fixedly sleeved with a first sealing ring, a second sealing ring and a third sealing ring from top to bottom in sequence, the top of the first sealing ring is embedded in the bottoms ofthe sealing rubber strips, and then the top of the filtering hopper and the bottom of the drainage port are sealed; the second sealing ring and the third sealing ring are embedded in the annular grooves of the two positioning s