In addition to the effect of harmonized illumination and increased heat radiation, a LED illumination lamp provides an improved effect of hermetic seal, anti-vibration and waterproofing between components and assures prolonged life span. The illumination lamp comprises a body adapted to be placed on or around a target illumination object, a LED module lying inside the body and a cover mounted on a seat part of the body. The LED module has a printed circuit board affixed to the body and a group of red, green and blue LEDs attached to the printed circuit. The cover is provided with a semitransparent color-producing part capable of harmonizing colors of the light emitted from the LEDs and an air passageway for permitting the heat generated from the LED module to dissipate to the outside.