The invention discloses a package structure for a micro-sensor including a micro-cantilever for capturing a chemical substance. The package structure, according to the invention, includes a first substrate, a second substrate, and a casing. The first substrate thereon forms a processing circuit. The micro-sensor is bonded to a first upper surface of the first substrate and is electrically connected to the processing circuit capable of outputting a signal relative to the chemical substance sensed by the micro-sensor. The second substrate has a formed-through aperture. The second substrate is bonded to the first substrate such that the micro-sensor is disposed in the formed-through aperture. The casing is bonded to the second substrate and includes a reaction chamber in which the micro-cantilever is installed and a fluid containing the chemical substance flows into.