Abstract: The quality of nuclear fuel in a pressurized water reactor has a direct bearing on the reactor safety. The fuel rod length is an important indicator in the quality control of nuclear fuel. Its measurement by a manual comparison with standard lengths is gradually replaced by automatic measurement systems. However, a specific and systematic verification and monitoring method for such systems has not yet been developed. This paper proposes a method for verifying an automatic length measurement system for fuel rods based on the investigation of the measurement system. An in-use automatic length measurement system was assessed by using this method.