The utility model relates to an observation window lighting device for insulating looped netowrk cabinet, including the looped netowrk cabinet, be the instrument room on the upper portion of looped netowrk cabinet, be the mechanism room in the below of instrument room, install the instrument room door in the front side of instrument room, the left side of mechanism room open have about two observation windows, install power supply unit bottom instrument room door inboard, have the adjust knob who is connected with the power supply unit wire at the mid -mounting of instrument room door, install the source of illumination who is connected with the adjust knob wire respectively above two observation window inboards of mechanism room. The utility model discloses a set up lighting circuit on the observation window, effectual illumination of looped netowrk cabinet isolator disconnection -connection states observation window and the earthing switch disconnection -connection states observation window realized throws light on, and power supply unit is waterproof dustproof, and the lighting circuit knob is adjustable, has adopted a plurality of light -emitting diode planar structure light sources simultaneously, has improved illumination brightness greatly, has prolonged isolator 0.