The thermal insulation vent is flexible to open and close, is tightly locked, and isolates internal and external high and low temperature transmission. The internal temperature of the vent basically does not change significantly with the external ambient temperature in winter and summer, effectively solving the problems of temperature rise, condensation, water leakage and insect infestation from the bottom of the granary. It is difficult to use, heat-insulated and moisture-proof, rain-proof and waterproof, sturdy and durable, beautiful and elegant, flexible and quick to open and close, easy to use, and can be conveniently connected with mobile ventilators, mobile circulation fumigators, grain coolers, and can also be installed at the air duct opening Adding a PH3 deliquescent device is an ideal grain protection infrastructure and replacement product for grain depots. The new insulation vents can be designed and manufactured according to the size of the original air duct openings. The vents can be modified without disassembling the original vents. This will not affect grain storage and is quick and easy to install and use.