developing process using a mask having hollow areas to develop to directly manufacture the porous thermoelectric thin film having a reticular structure on the substrate and when the porous thermoelectric thin film is the etching process using an etching technique to directly etch the thermoelectric material as the porous thermoelectric thin film having a porous boundary on the thermoelectric material wherein a thickness of the thermoelectric material is between 5 nm and 5 u03bcm when the thick is too thick surfaces of the thin film engage with each other enabling that the decline of the thermal transfer coefficient decreases to the contrary when the thickness is too thin tie strength of the thermoelectric material is not enough and easy to break which leads a completed thin film cannot be formed consequently it results the free electron in the thermoelectric material not being able to move smoothly such that the electrical conductivity decreases in sst 2 respectively constructing contact electrodes at two ends of the porous thermoelectric thin film to enable the porous thermoelectric thin film guiding an electrical energy converted from a thermal energy for using wherein the thermoelectric material comprises a rare earth element compound a silicon based material a semiconductor material a ferromagnetic material or a metal material and when the thermoelectric material is the ferromagnetic material using an external magnetic field to provide diverse magnetic.