An outdoor LED lamp includes an LED lamp and a cover mounted on the LED lamp and covering a heat sink of the LED lamp therein. The LED lamp includes a bracket, the heat sink mounted on a top side of the bracket, and a plurality of LED modules mounted on a bottom surface of the heat sink. The cover is a bended metal sheet. The cover includes a covering portion located over a top of the heat sink and a baffling portion extending slantwise downwardly from an end of the covering portion. Height of the covering portion is decreased from a central portion to opposite lateral portions of the covering portion. Slits are defined in the covering portion. Downwardly opened slots are defined in the baffling portion. The cover is used for preventing snow, leaves or dust from accumulating on the heat sink.