The invention provides a reciprocating type rope length measuring device, which comprises a sliding rod and two H-shaped frames. The two ends of the sliding rod are respectively and fixedly connectedto the middle parts of the H-shaped frames; the sliding rod and a sliding block are in sliding connection; and limiting blocks are fixedly connected to the two sides of the sliding rod. A rope clamping device is fixedly connected to the bottom of the sliding block. A fixed gear is fixedly connected to the side wall of the sliding block; and a travel switch is connected to the top of the sliding block. A first drive motor is fixedly installed at the bottom of a cross beam in the middle of one H-shaped frame; and a drive shaft of the first drive motor is fixedly connected with a first rotating gear. A fixation block is fixedly connected to the bottom of the cross beam in the middle of the other H-shaped frame and is in rotation connection with a second rotating gear; tooth-shaped belts sleeve the first rotating gear and the second rotating gear; and the inner sides of the tooth-shaped belts are in contact and connected with the fixed gear. A scale ruler is fixedly connected to vertical rods at the front sides of the H-shaped frames. Therefore, the efficiency of measuring the length of the rope is improved; the labor cost is lowered; and the accuracy of the rope length measurement isimproved.