Abstract: Industrial endoscope is used in the areas where human eyes are unable to observe during the full scale aircraft structural fatigue test. Indirect visual inspection is realized by means of Image conversion between objective lens and liquid crystal display. Under the premise the assemblies are not removed or destroyed, the inner surface structures or working conditions of assemblies can be observed and detected conveniently and quickly. The crack length is measured at the same time. Consequently the effective quality management is well implemented.