The utility model provides a gas collection tank for the core gas of a natural gas hydrate drilling gate, which comprises a tank body and a tank body cover, wherein the tank body is of a cylindrical structure with an open upper end and a closed lower end; and the tank body cover is a detachable gas collection and guide device sleeved at the open end of the tank body and forms sliding sealing connection with the tank body through a sealing ring. The gas collection tank provided by the utility model is very convenient to operate; the whole process from encapsulation of hydrate core sample, gas release to gas collection is finished once; and a series of middle processes are simplified, and the gas collection efficiency is greatly improved.