Abstract: The invention is a silicon pressure micro-sensing device and the fabrication process thereof. The silicon pressure micro-sensing device includes a pressure chamber, and is constituted of a P-type substrate with a taper chamber and an N-type epitaxial layer thereon. On the N-type epitaxial layer are a plurality of piezo-resistance sensing units which sense deformation caused by pressure. The fabrication pressure of the silicon pressure micro-sensing device includes a step of first making a plurality of holes on the N-type epitaxial layer to reach the P-type substrate beneath. Then, by an anisotropic etching stop technique, in which etchant pass through the holes, a taper chamber is formed in the P-type substrate. Finally, an insulating material is applied to seal the holes, thus attaining the silicon pressure micro-sensing device that is able to sense pressure differences between two ends thereof.