The invention relates to a mechanism for quickly forming an ice valve and improving the strength of the ice valve, which is used for the quick in-situ generation of the ice valve on a natural gas hydrate ice valve type pressure maintaining and heat insulation sampler, and used for enhancing the carrying capability. More than one circular groove is arranged on the inner wall of an ice valve pipe, more than three elastic fins are arranged between the two circular grooves along the peripheral direction with equal angles, the lower end of the elastic fin is fixed on the inner wall of the ice valve pipe by a rivet and is fixed firmly by brazing, and a lower end cover is in threaded connection with an outer circulating pipe and in static fit with the ice valve pipe. According to the design of the elastic fins, the contact area between drilling fluid and a low-temperature object is enlarged, the heat exchange efficiency is improved, and the generation of the drilling fluid ice valve is accelerated; and after the drilling fluid ice valve is formed, the elastic fins have the framework supporting function to the ice valve, thereby enhancing the carrying capability of the valve, improving the sampling rate, and reducing the cost.