The invention relates to a noise reduction structure of main noise resources of an urban indoor substation, belonging to the technical field of noise pollution control in environmental engineering. The noise reduction structure is mainly used for reducing the noise resources of the urban indoor substation, including noise radiated by a main transformer and a reactor 1. The noise reduction structure comprises a wall perforated plate resonance sound absorption structure 2, a sound isolation door 3, a ventilating shutter 4, a low-noise axial flow fan 5, an air intake silencer 6 and an air exhaust silencer 7, wherein the wall perforated plate resonance absorption structure 2 is located inside the wall and comprises a perforated gypsum plate and acrylic cotton; the sound isolation door 3 is filled with glass coated intermediate glass cotton fiber, and the gap of a door frame is filled with sealing strips; the ventilating shutter 4 and the low-noise axial flow fan 5 are used for ventilating and dissipating heat to ensure the safe and stable operation of the main transformer and the reactor; the air intake silencer 6 is installed on the outer part of the ventilating shutter 4, the upper part is a lighting sound-isolating window cover, and the lower part is an air flow channel covering the sound absorption material; and the air exhaust silencer 7 is installed outside a ventilating fan hole, and the interior is an air flow channel covering the sound absorption material.