A sliding cover-opening device, comprising: a top support located on an upper portion of a main body of a cigarette case, wherein an overall structure of the top support is a hollow frame having walls for fixing other elements and holes for other elements to extend out; two side walls opposite to each other are provided with a pair of sliding grooves, one of the two side walls is provided with a cigarette case snap-fit hole, and the other one of the two side walls is fixedly connected to a spring fixing plate on the cigarette case; a sliding-resistant device located inside the hollow frame of the top support, wherein the sliding-resistant device comprises a cylindrical spring cap, a spring threaded seat located on a lower portion of the cylindrical spring cap and fixedly connected to the cylindrical spring cap, a cover pushing spring located inside the cylindrical spring cap, and a hemispherical spring head located on an upper portion of the cylindrical spring cap and connected to the cover pushing spring; a rotatable cover opening device, wherein the rotatable cover opening device comprises a rotatable pushing cover, one segment of the rotatable pushing cover is in a form of cover for covering at least a part of an upper surface of the top support, and an end of the segment is provided with a snap-fit block matched with the cigarette case snap-fit hole; another segment of the rotatable pushing cover is a pair of symmetrically separated blocks, each of the separated blocks is provided with a sliding rotating groove, a connection part of the two segments is a cylinder body, two ends of the cylinder body are respectively provided with a rotating locating pin, the rotating locating pin is arranged inside the sliding groove and capable of rotating freely and moving horizontally; the rotatable cover opening device further comprises a rotating torsional spring, a main body of the torsional spring is wound on a cylinder body of a fixed support, one end of the rotating torsional spring is fixedly connected inside the sliding rotating groove, and the other end of the rotating torsional spring is fixed by the spring fixing plate. a top support located on an upper portion of a main body of a cigarette case, wherein an overall structure of the top support is a hollow frame having walls for fixing other elements and holes for other elements to extend out; two side walls opposite to each other are provided with a pair of sliding grooves, one of the two side walls is provided with a cigarette case snap-fit hole, and the other one of the two side walls is fixedly connected to a spring fixing plate on the cigarette case; a sliding-resistant device located inside the hollow frame of the top support, wherein the sliding-resistant device comprises a cylindrical spring cap, a spring threaded seat located on a lower portion of the cylindrical spring cap and fixedly connected to the cylindrical spring cap, a cover pushing spring located inside the cylindrical spring cap, and a hemispherical spring head located on an upper portion of the cylindrical spring cap and connected to the cover pushing spring; a rotatable cover opening device, wherein the rotatable cover opening device comprises a rotatable pushing cover, one segment of the rotatable pushing cover is in a form of cover for covering at least a part of an upper surface of the top support, and an end of the segment is provided with a snap-fit block matched with the cigarette case snap-fit hole; another segment of the rotatable pushing cover is a pair of symmetrically separated blocks, each of the separated blocks is provided with a sliding rotating groove, a connection part of the two segments is a cylinder body, two ends of the cylinder body are respectively provided with a rotating locating pin, the rotating locating pin is arranged inside the sliding groove and capable of rotating freely and moving horizontally; the rotatable cover opening device further comprises a rotating torsional spring, a main body of the torsional spring is wound on a cylinder body of a fixed support, one end of the rotating torsional spring is fixedly connected inside the sliding rotating groove, and the other end of the rotating torsional spring is fixed by the spring fixing plate.