According to the invention, a safety mark time device for replacing a rubber sleeve of a coil core of a steel coil winding machine is provided. The device comprises two supporting parts and a moving part, wherein each supporting part comprises a support and two guide rails which are arranged in parallel, one ends of the guide rails are located on the ground, the other ends of the guide rails are located on cantilever ends of the supports, and a fixing component used for fixing the moving part is further arranged on the guide rails; the moving part comprises a mark time frame, a plurality of rolling wheels, two handrails arranged on the upper part of the mark time frame, wherein the mark time frame is in a plate shape, a plurality of rolling wheel supports are arranged at the lower part ofthe mark time frame, and the rolling wheels are arranged on the rolling wheel supports; and the moving parts move from one side of a deep pit opening to the other side of the deep pit opening, when the rolling wheels at one ends leaves away from the cantilever ends of the supports, and the rest of the rolling wheels of the moving parts bear the moving part to continuously and stably move until thesuspended rolling wheels reach the guide rails at the other sides. According to the safety mark time device, spatial arrangement of a special position is utilized, the device is specially used for replacing the rubber sleeve of the coil core of the steel coil winding machine, and has the advantages of being high in efficiency and short in replacement time.