In order to discuss the spills from LNG carriers and accident consequences, this article builds LNG discharge rate model. A double-hull membrane-type LNG ship as one spill example case is considered, which has five tanks, each averaging 35000m3 of LNG. The two conditions are researched as follows, in the event of underwater penetration of a double-hull ship with only the outer wall, both outer hull and LNG tank breached. LNG development in initial response period and LNG evaporation adding to hull pressure are analyzed. The range of ice is also researched in this paper, forecasting the accident consequences in the end.