Abstract: Objective: To assess the applicability and accuracy of Demirjian, Willems, Haavikko methods in estimating the dental age of Nanjing children. Methods: A total of 450 panoramic radiographs (263 males and 187 females) of Nanjing children were collected for the study on the basis of predetermined inclusion and exclusion criteria. Dental age was calculated using Demirjian, Willems, and Haavikko methods and the difference between estimated dental age and chronological age were compared with paired t-test. Results: Demirjian method overestimated age 0.50 years(boys 0.48 and girls 0.53); Willems method overestimated 0.02 years(boys 0.09 and girls 0.07); Haavikko method underestimated 0.85 years(boys 0.87 and girls 0.82). For individual tooth using Haavikko’s method, the first molar method underestimated 0.42 years(boys 0.45 and girls 0.36)；the center incisor underestimated 0.65 years(boys 0.66 and girls 0.61). Conclusions: Willems’s method was more accurate in estimating dental age compared to other methods. It is followed by Demirjian and Haavikko method; for individual tooth using Haavikko’s method, first molar and central incisor were more accurate than the mean value of all developing teeth.