The invention provides a novel bunkering storage tank system for a ship and a liquefied natural gas (LNG) bunkering pontoon with the storage tank system. The storage tank system comprises a tank body, a pipe system and an immersed pump. The tank body is provided with a tank main body for LNG storage. The pipe system comprises a liquid feeding pipe and a liquid discharge pipe. The liquid feeding pipe and the liquid discharge pipe stretch into the tank main body from the top of the tank main body. The immersed pump is installed at the bottom in the tank main body and is connected to the liquid discharge pipe. LNG in the tank main body is pumped into the liquid discharge pipe and is bunkered outside. The LNG bunkering pontoon comprises a pontoon body, at least one storage tank system on the pontoon body and a bunkering system connected to the storage tank system. The novel bunkering storage tank system for a ship can reduce BOG production, improves operating economics and safety, is free of a connection pipe system between the tank main body, and a pump tank and the pump, reduces a cofferdam and a cooling box and reduces a construction cost.