Sleeping bag

A sleeping bag comprises a pad body part and a cover part, wherein the pad body part and cover part form a horizontal lying space together. The pad body part comprises a pad body surface layer, a pad body inner layer and a lower interlayer element which is combined with the pad body surface layer and the pad body inner layer to form a lower inflatable space; the cover part comprises a cover inner layer, a cover surface layer and an upper interlayer element which is combined between the cover inner layer and the cover surface layer; the lower inflatable space is provided with a plurality of inflatable passages and at least one connecting passage which is provided with an air port and connected with the inflatable passages; and the pad body part further comprises an inflation valve seat used for closing and opening the air port. The sleeping bag has the advantages that the air is used for increasing the thickness of the pad body part, the comfort level of horizontal lying can be improved, and when the air is di