A package substrate of the present invention at least comprises a metal substrate and a plurality of light emitting dies. The metal substrate is provided thereon with at least one trench. The trench is recessed into the surface of the metal substrate through an insulating layer. The light emitting dies are secured in the trench and electrically connected to a predetermined wiring layer on the metal substrate by metal wires, thereby obtaining a light emitting die package substrate with good thermal conductivity, high heat dissipation, separate electrical and thermal paths and a simple and firm structure.