The invention discloses a length-width-adjustable quick take-up and pay-off device applicable to different models of cable reels and a method for applying the length-width-adjustable quick take-up and pay-off device. The length-width-adjustable quick take-up and pay-off device comprises a U-shaped frame. Universal self-locking rollers are arranged at four corners of the U-shaped frame, extension rods which are perpendicular to transverse rods are arranged on the inner sides of free ends of the two transverse rods of the U-shaped frame, connecting rods which are hinged to each other in a crossed manner are arranged at the ends of the extension rods, the other end of each connecting rod is in cup joint with the free end of the other corresponding extension rod in a crossed manner, two cable reel sliding mechanisms sleeve each connecting rod, the length of each extension rod is larger than the width of each cable reel sliding mechanism, guide sleeves sleeve the two transverse rods of the U-shaped frame and are connected with each other by a fixing rod, two driving rollers which are rotationally connected with the fixing rod sleeve the fixing rod, annular grooves are formed in the peripheral sides of the driving rollers, the cable reels can be clamped in the annular grooves, and the center of a side of the fixing rod is connected with the center of a vertical rod of the U-shaped frame by a hydraulic ejector rod.