The invention discloses a vertical length measuring device which comprises the components of a height adjusting part, wherein the height adjusting part is composed of a base, a supporting rod and an adjusting nut; a lead part which is composed of a left transverse guide roller, a right transverse guide roller, a left vertical guide roller, a right vertical guide roller, a left bracket and a right bracket; a floating tracking part which is composed of a swinging side plate, a length measuring wheel, a vertical rod and a spring; a length measuring device part which is composed of the length measuring wheel and a tachometer, and a line pressing part which is composed of a supporting rod, a wire pressing wheel board and a wire pressing wheel. The vertical type length measuring device has a reasonable and reliable structure. Not only can height of the length measuring wheel be adjusted according to the diameter of a cable for adapting with the diameter range of the cable, but also the length measuring wheel always abuts against the external circle of the cable through floating support of the spring. High use performance and high length measuring precision are realized. Particularly, the length of the cable can be accurately measured in relatively high horizontal movement speed of the cable.