as shown in fig3 and 4 as shown in fig1 and 7 an upper portion of the door seal 3 is snapped in the groove 211 and a lower portion of the door seal 3 is pressed against the top portion of the shell 1 hermetically when the door body 2 is closed as shown in fig1 an air passage 4 is formed between the door seal 3 and the groove 211 when the door body 2 is subjected to an upward external force as shown in fig5 and 6 specifically as shown in fig1 and 2 the door body 2 is in a close state and at this time the door seal 3 is compressed under a pressure due to a weight of the door body 2 so that a seal is formed between the door body 2 and the shell 1 and a hot and cool air exchange between an inside of the shell 1 and an outside environment does not occur such that the effect for storing food is good as shown in fig5 and 6 when the door is needed to be opened a user may raise the door vigorously i e provide an upward external force to the door at this time the air passage 4 is formed between the door seal 3 and the groove 211 and the external air may enter into the shell 1 via the air passage 4 thus balancing the internal pressure and the external pressure of the shell 1 so the door is easy to be opened meanwhile since the upper portion of the door seal 3 is snapped in the groove 211 although.