The utility model discloses an indoor security protection alarm device of electric power system, including the mounting box, the mounting box includes the diapire, the left side wall, the right side wall, box body and closing cap are formed to back lateral wall, the closing cap comprises top cap and protecgulum, the installation pole is equipped with admittedly to the bottom surface of diapire, the top surface of diapire is equipped with the bracing piece admittedly, the mounting panel is equipped with admittedly at the top of bracing piece, install level sensor on the mounting panel, penetrating hole has been seted up at the middle part of mounting panel, surround last penetrating hole on the mounting panel and offered the fixed orifices, correspond to go up penetrating hole on the diapire and set up the lower penetrating hole that the measuring staff that can supply level sensor passed, the rear side wall mounting has power and controller, level sensor is connected with the controller electricity, installs smoke transducer and sulfur dioxide sensor on the top cap, has seted up the bleeder vent on the diapire, has seted up the fish scale hole on left side wall and the right side wall, install infrared sensor in the mounting box, correspond infrared sensor signal detection department on the mounting box and seted up detection port.