Diameter-variable assembly and diameter-variable sealing equipment

The invention provides a diameter-variable assembly and diameter-variable sealing equipment comprising the diameter-variable assembly. The diameter-variable assembly comprises a sliding sleeve, a first limiting sleeve, a second limiting sleeve, a sealing sleeve and an inner fixing sleeve, wherein the first limiting sleeve and the second limiting sleeve are arranged at two ends of the inner fixing sleeve respectively; the sliding sleeve is spliced by at least two sliding branch sections, two ends of each sliding branch section are mounted in the first limiting sleeve and the second limiting sleeve respectively and are in radial sliding fit with the first limiting sleeve and the second limiting sleeve respectively; the outer wall of the sealing sleeve is in seal fit with the inner wall surface of the sliding sleeve, the sealing sleeve is spliced by at least two sealing branch sections, and each splicing gap of the sliding branch sections corresponds to one sealing branch section. When the outer diameter of the