A thermal bag includes a thermal bag main body and a zipper. The thermal bag main body includes an accommodating portion and an opening portion. The accommodating portion is connected to the opening portion to form the thermal bag. The opening portion is formed with an opening. The opening is mounted with the zipper. Two support bars are interlaid between an outer layer fabric and an inner layer fabric of the opening portion at two sides of the zipper, respectively. The two support bars extend in the direction of the opening. When the zipper is unzipped, the two support bars cooperate with each other to brace the fabrics of the opening portion, so that the opening is formed in a stable shape, does not collapse and is more convenient for taking and placing articles.