The invention relates to a sleeve capable of preventing a nut and a spacer from falling off. The sleeve comprises a cylinder and an adapter, the adapter is detachably connected on the cylinder, a placing groove is formed in one end of the adapter, a through hole is formed in the placing groove, a magnet absorption component is arranged in the cylinder, one end of the magnet absorption component is arranged in the through hole, a push component is arranged in the cylinder, a reset spring is arranged in the cylinder, one end of the reset spring is connected with the magnet absorption component, the other end of the reset spring is connected with the push component, and an absorption magnet is arranged on the adapter. The sleeve has the advantages that the nut is sucked in the placing groove by the magnet absorption component, the spacer is sucked in the placing groove by the absorption magnet, the nut can be conveniently and rapidly fastened by rotating the cylinder in the live working process, the nut and the spacer can be effectively prevented from falling off in the live working process, time of operating workers contacting with an electrified body is greatly shortened in the live working process, times of the operating workers contacting with the electrified body is decreased in the live working process, live working safety coefficients are greatly improved, and working efficiency is improved.