The utility model provides a whole-circle backoff demoulding mechanism. The whole-circle backoff demoulding mechanism comprises a core block pull rod, wherein the core block pull rod is sleeved with a fixed sleeve; the circumference of the top of the core block pull rod is provided with multiple inclined guiding grooves, wherein the inclined directions of the inclined guiding grooves are inclined from top to bottom and from inside to outside, and each inclined guiding groove is internally provided with a core block in a sliding manner; the inner sides of the core blocks are guiding inclined surfaces matched with the inclined guiding grooves, external molded surfaces of the core blocks can form a round flange step together, and the round flange step is coincided with an internal molded surface of a product back-off part. The whole-circle backoff demoulding mechanism provided by the utility model has the advantages that the structure is simple, the core block pull rod downward moves to drive the core block to do a circular movement, and a backoff can be demoulded; the inclined guiding grooves are set into two different slopes, two corresponding core blocks have different routes, the sizes of flanges formed by the external molded surfaces of the core blocks are further reduced, so that the whole-circle backoff demoulding mechanism is beneficial to smoothly demoulding, and the purposes that the production efficiency is improved, the cost is reduced, and an accident potential is eliminated are achieved.