The invention provides a cable measuring device comprising a measuring rod component which is provided with a fixed plate; a moving plate which is movably installed on the measuring rod component, wherein a cable clamping space is formed between the moving plate and the fixed plate; and a measuring scale which is installed on the measuring rod component so as to detect the moving distance of the moving plate. According to the cable measuring device, the problem in the prior art that the diameter of a cable having high voltage is difficult to detect can be solved.