The invention relates to the field of measurement, in particular to a rod length measuring device. The rod length measuring device comprises a platform, a feeding frame, a discharging frame and a material moving assembly, wherein a to-be-measured long rod is placed on the feeding frame; an already-measured long rod is placed on the discharging frame; the feeding frame is arranged at one side of the platform width direction; the discharging frame is arranged at the other side of the platform direction; the material moving assembly is arranged in the middle part of the platform width direction;the material moving assembly comprises a length measuring groove; the material moving assembly is used for taking a material from the feeding frame, moving the to-be-measured long rod to the length measuring groove and moving the already-measured long rod in the length measuring groove to the discharging frame. In use, material taking is realized through the material moving assembly, the already-measured long rod is moved to the discharging frame after length measurement is completed, the process is completed through the material moving device, and the measurement efficiency is improved. The device can be used for cladding tube length measurement with high precision requirements and can also be used for length measurmenet for other rods or a straight tube.