Objective To investigate the cognition and behaviors of sun-protection and the facial photoaging in a Nanjing population, and to analyze the relationships between them. Methods The objects being investigated in Nanjing (n=974) were divided into 10 groups according to age. The ordinary information, knowledge and behavior of sun-protection and Glogau photoageing type of face were studied by questionnaires. The results were analyzed by a logistic regression model to select the related factors to photoageing. Results The risk of skin photoageing increased with age. Most of the 46-65 years old crowds were type Ⅲ photoageing. Most of the objects being investigated had some knowledge and active awareness of sun-protection and could use some ways to protect themselves from sun. However, most people did not use the sunscreen correctly. Those who had higher level awareness and knowledge of sunprotection suffered less risk from skin photoageing. Sunbath without sunscreen for a long time outside activity was a high risk factor of development to skin photoageing. Shade, broad-brimmed hat and sun-protection in autumn were the protective factors. Conclusion Active awareness and correct methods could help prevent skin photoageing. In order to avoid the damages to skin from ultraviolet efficiently, the accurate ways of using sunscreens should be well understood.