An environmentally friendly energy saving device includes a hollow metal inner pipe inserted in a hollow metal outer pipe, and the inner pipe includes: a middle portion defining a receiving chamber with respect to the hollow metal outer pipe, two connecting portions located at two ends of the middle portion and extended out from two ends of the hollow metal outer pipe, and a thinning groove formed in the middle portion and in communication with the receiving chamber. Far infrared powder are filled into the receiving chamber and the thinning groove and pressurized into a block. Two ends of the receiving chamber are sealed. By thinning the part of the outer wall of the inner pipe that is connected to the receiving chamber, the energy-saving efficiency of the environmentally friendly energy saving device is improved.