The visual inspection threshold of dent damage and its influence factors must be determined during the aircraft composite structure design.Three kinds of punches with different diameters are used to introduce randomly distributed dent damage on the surface of plate by quasi-static method. The influence of three factors， such as the angle of the plate， color and the level of the inspector， on the results of the detailed visual inspection is investigated.Based on the cumulative lognormal distribution model， the detection probability of different factors is analyzed and compared. The results show that dent damage of the blue plate is easier to be detected； it is easier to detect the dent damage when the angle is close to the vertical； and the detection probability of the professional with maintenance or visual inspection experience is high.