A method of assembling a multi-layer LED array engine is provided. The method includes the steps of: preparing a base plate frame comprising at least one lighting area, and two lead frame grooves; positioning two lead frames inside accommodating spaces defined in the two lead frame grooves, respectively; executing an injection molding process to form a molded platform on the base plate frame; configuring a thin layer of nickel or chromium; arranging a plurality of LED dice in an array form on an upper surface of the base plate frame; electrically coupling the LED dice to the lead frames by bonded wires; forming a protection layer on the LED dice and the bonded wires; forming a phosphorous layer on the protection layer, wherein the phosphorous layer is formed within a range defined by the phosphorous wall; and forming a dome on the upper surface of the molded platform by executing an injection molding process.