A lamp includes a housing, a cooling module and a light emitting diode. The housing has an assembling opening and an electrical connection member on two ends of the housing, wherein an inner surface of the housing defines a receiving room, and a part of the inner surface of the housing adjacent to the assembling opening is an air-guiding wall. The cooling module is disposed at the assembling opening of the housing to form at least one air channel between the cooling module and the air-guiding wall, wherein the cooling module has an air-guiding passage communicating with the receiving room of the housing. The light emitting diode is coupled with the cooling module. Therefore, there is no air inlet or outlet formed on the housing of the LED lamp, so as to provide a simplified structure and to maintain the exterior integrity of the LED lamp.