A lamp structure of an adaptive streetlight includes a housing, a plurality of light sources, and a surface-structured diffusion plate. The surface-structured diffusion plate enables the lamp structure to provide a light pattern conforming to the curvature of the road to be illuminated or other sites of application, thus reducing not only the number of lamps or streetlights required for a curvy road section, but also the associated installation cost and power consumption. The lamp structure can enhance road users' safety and the safety of our daily lives by increasing the illuminance on a curvy road and other sites of application that have special requirements.