The invention provides a porous conductive elastic body based stress sensor and a manufacturing method thereof. The stress sensor comprises a planar electrode (1), a conductive elastic body (2) of a porous structure and a planar electrode (3), the planar electrode (1) is bonded and connected to the upper surface of the porous conductive elastic body (2), the planar electrode (3) is bonded and connected to the lower surface of the porous conductive elastic body (2), and the planar electrode (1) and the planar electrode (3) serve as signal output ends of the stress sensor. The porous conductiveelastic body based stress sensor can make response accurately to outside stress change via resistance change, and has advantages of high stability and reliability. The stress sensor also has high mechanical and electrical performances, key parameters as the sensitivity of the stress sensor are regulated and optimized by adjusting the mass fraction, aperture and porosity among different compositions, and an outside mini stress can be identified accurately.