A package structure of an optical module includes: a substrate having a frame defined with a light-emitting region and a light-admitting region; a light-emitting chip disposed at the light-emitting region of the substrate; a light-admitting chip disposed at the light-admitting region of the substrate; two encapsulants formed in the frame and enclosing the light-emitting chip and the light-admitting chip, respectively; and a shielding layer formed on the frame and the encapsulants and having a light-emitting hole and a light-admitting hole, wherein the light-emitting hole and the light-admitting hole are positioned above the light-emitting chip and the light-admitting chip, respectively. The optical module package structure uses an opaque glue to reduce costs and total thickness of the package structure.