Abstract: Impact damage was the key damage type encountered by composite structures in service, which can produce permanent dents. In order to obtain the probability of detection(POD)of dents, the maximum likelihood method was used to calculate parameters of two POD models (the cumulative lognormal model and the log odds model) for general visual inspection (GVI) and detailed visual inspection (DET). Experimental DET study was performed and POD models were verified by test data. The results indicate that the cumulative lognormal model is fit for the POD of dents. Compare with black boards, the dents on green boards can be detected easier, and with the increase of inspection angle, the dents are more likely to be detected. Barely visible impact damage (BVID) thresholds are between 0.35 mm and 0.8 mm.