The present invention discloses a lamp structure. An accommodating cavity is provided for disposing a lamp board. An insulating unit seals the opening of the accommodating cavity for preventing accidental electric shocks when a user cleans or maintains the lamp structure. Placing the lamp board inside the accommodating cavity, the space occupied by the lamp board on the base may be saved. The insulating unit may prevent foreign matters or water from contacting the lamp board and resulting in short circuit or failure in the lamp board. One or more heat dissipating unit may be disposed in the accommodating cavity and used as the heat dissipating structure for the lamp board. A recess may be disposed on an inner side of the accommodating cavity. The recess communicates with the accommodating cavity. A capacitor may be disposed in the recess and connected electrically to the lamp board.