This present invention relates to a eco-friendly ultra-high temperature thermal decomposition system for waste-to-energy, where its thermal decomposition chamber made with special castable mixture maintains the ultra-high temperature above 850° C. and ten (10) layers of air curtains made by a double-layered air-curtain maker installed at the center of the thermal decomposition chamber allows the input materials to be completely decomposed without any auxiliary fuel and air pollutants to be completely decomposed by trapping them inside the thermal decomposition chamber with ultra-high temperature above 850° C. for more than two (2) seconds of residence time, as well as its two (2) layers of oil nozzles, central oil nozzles and lower oil nozzles, installed on the inner wall of the thermal decomposition chamber, each installed to aim the central part and the bottom part of the thermal decomposition chamber, evenly spraying the auxiliary fuel when necessary so the input materials with different conditions, sizes, and hydration level, are completely decomposed; furthermore, its outer shredder, installed at the left side of the thermal decomposition chamber, improves its treatment efficacy by homogenizing the input materials with different conditions, sizes, and hydration level, prior to being fed into the thermal decomposition chamber, with a screw conveyor connecting the outer shredder and the thermal decomposition chamber automatically feeding the input materials, as well as its inner shredder installed at the bottom part of the thermal decomposition chamber shreds the ash and the input materials that are not being decomposed yet piled up at the bottom of the thermal decomposition chamber so the screw conveyor connecting the inner shredder and the thermal decomposition chamber can re-input such materials back to the thermal decomposition chamber, thus even the ash is also completely decomposed; moreover, its thermal generation modules, installed in the thermal generation chamber around the thermal decomposition chamber and on the upper cover of the thermal decomposition chamber, effectively collect the waste heat generated from thermal decomposition process to generate electricity while the waste heat is also used to generate steam via the steam chamber installed on the upper cover of the thermal decomposition chamber, where such steam is sent to separately composed boiler and steam turbine via steam pipe to generate further electricity; and lastly, its dust collector and the monitoring device are located at the right side of the thermal decomposition chamber with their collecting holes at the top part of inner wall of the thermal decomposition chamber to collect the dust when necessary and the air samples to monitor the results of the thermal decomposition process in real time.