A retractable cable management device, comprising a strip-shaped housing and a sliding device; wherein the housing is provided with an opening formed along the length direction of the housing, an input cable is provided at one end of the housing, an output cable is provided at the other end of the housing, and the two ends of the housing are provided with closed end covers; and one end of the sliding device extends into the housing through the opening and is electrically connected to the input cable and the output cable; wherein the sliding device can slide along the length direction of the opening and the extension length of the output cable relative to the housing changes accordingly during sliding; wherein the sliding device is a tightening mechanism with one end inserted into the opening, the other end exposed outside the housing and comprising a limit post that can move along the length direction of the opening, characterized by a fastening knob that is threaded to the limit post and has a nut located outside the housing, wherein the moving position of the tightening mechanism relative to the opening can be adjusted by loosening and tightening the fastening knob to change the fixed tightness between the tightening mechanism and the housing so that the length of the output cable extending out of the housing can be changed, and the housing is provided with a partition formed along the length direction of the housing, the partition divides the cavity of the housing into an upper cavity and a lower cavity, the opening is provided in the lower cavity portion, the input cable extends from the upper cavity to the other end of the housing and is connected to the output cable as a whole, and a bent portion of the output cable at the other end of the housing connected to the input cable is fixed in the end cover by abutting the corresponding end of the partition. the housing is provided with an opening formed along the length direction of the housing, an input cable is provided at one end of the housing, an output cable is provided at the other end of the housing, and the two ends of the housing are provided with closed end covers; and one end of the sliding device extends into the housing through the opening and is electrically connected to the input cable and the output cable; wherein the sliding device can slide along the length direction of the opening and the extension length of the output cable relative to the housing changes accordingly during sliding; wherein the sliding device is a tightening mechanism with one end inserted into the opening, the other end exposed outside the housing and comprising a limit post that can move along the length direction of the opening, characterized by a fastening knob that is threaded to the limit post and has a nut located outside the housing, wherein the moving position of the tightening mechanism relative to the opening can be adjusted by loosening and tightening the fastening knob to change the fixed tightness between the tightening mechanism and the housing so that the length of the output cable extending out of the housing can be changed, and the housing is provided with a partition formed along the length direction of the housing, the partition divides the cavity of the housing into an upper cavity and a lower cavity, the opening is provided in the lower cavity portion, the input cable extends from the upper cavity to the other end of the housing and is connected to the output cable as a whole, and a bent portion of the output cable at the other end of the housing connected to the input cable is fixed in the end cover by abutting the corresponding end of the partition.