A underground granary used for storing grains in bulk comprises a grain storage floor, a mechanical floor, a multifunctional vertical channel and the like, wherein the multifunctional vertical channel is located in the middle part of the granary body and connected with a granary base plate, an interlamination plate, a granary head cover and the ground, and a multifunctional opening is arranged on the wall and the inside of the multifunctional opening is used for installing vertical transportation facilities. The multifunctional opening is communicated with the grain storage floor and the mechanical floor of the granary body. The inside of the granary body can be entered into through the multifunctional opening, and the ventilation of the granary body, the examining and repairing by manual work and the maintenance of equipment are achieved. Grain warehousing shunting pocket bags are installed on the top of the multifunctional vertical channel and even warehousing operations of the granary body are achieved. A cone-shaped hopper arranged on the interlamination plate is used for flowing automatically of the grains. A horizontal transportation device is installed on the granary base plate of the ground floor and transports the grains flowing automatically down from the cone-shaped hopper into the vertical transportation device. High-efficiency taking out of granary work is achieved. The underground grain storing new granary is used for achieving the green grain storing manner of the long shelf-life, and fully develops and applies the underground space and the shallow geothermal energy and has important research values.