The utility model discloses a buckle formula heat shrinkage bush for loosening cover optical cable, including square pyrocondensation piece (1), and establish the spill card sealing (3) and the convex on square pyrocondensation piece (1) two relative limits buckle sealing (4), spill card sealing (3) the concave part with the convex convex part of detaining sealing (4) correspond the heat shrinkage bush that forms protection pine cover optical cable behind the lock. The utility model discloses following beneficial effect has: simple structure, convenient to use, the material is easy, and application scope is wide, not only can open for loose cover optical cable and shell mouthful increase mechanical strength of department, can also prevent a large amount of losses of the inside liquid grease of pine cover optical cable, more importantly can be in the optional position installation or the replacement of the loose cover optical cable of big length.