A method of manufacturing a pressure sensor is provided. The method includes: providing a substrate, wherein a bottom electrode and a pressure sensing film are disposed on the substrate; forming an etch stop assembly on the pressure sensing film at a location corresponding to a pressure trench; forming a cover layer on the substrate covering the etch stop assembly and the pressure sensing film; forming a mask layer on the cover layer, wherein an opening of the mask layer is formed above the etch stop assembly and exposes a portion of the cover layer at the location corresponding to the pressure trench; etching the cover layer using the mask layer so as to form the pressure trench in the cover layer; removing the etch stop assembly at a bottom of the pressure trench; and removing the mask layer.