A computer data line length measuring instrument, the measuring instrument comprises a housing, a moving block mechanism is disposed on the top of the housing, the moving block mechanism is fixedly connected to the moving plate, the moving plate is fixedly connected to the transmission belt mechanism and the support plate mechanism, and the top of the housing is fixedly connected to the drive mechanism. The drive mechanism and the moving block mechanism are disposed between the transmission mechanism, the top of the housing is provided with a movable groove, the inside of the housing is fixedly connected with a height adjustment mechanism, the height adjustment mechanism is fixedly connected with a rotatable mechanism, and the rotatable mechanism is fixedly connected with a blade mechanism. A plurality of card line measuring mechanisms are arranged on the blade mechanism. The present invention is able to drive the mobile block mechanism to drive the mobile plate to move, and then drive the transmission belt mechanism and the support plate mechanism to move, thereby tightening the computer data lines of different diameters. The transmission belt mechanism is able to drive the computer data line to move, thereby realizing continuous batch length measurement, and the support plate mechanism is able to support the computer data line to avoid sliding.