A lamp structure for a ceiling fan has a connecting part at the top of its lamp base to connect to a ceiling fan. An installing part has at least two slant surfaces facing obliquely downward when the lamp base is connected to the ceiling fan. The slant surfaces are symmetric with respect to the lamp base. Each of the slant surfaces has a light-emitting diode whose light-emitting direction is also obliquely downward as the corresponding slant surface.