The utility model discloses a box -type substation pick -proof door alarm, including the main tank body, the front connection of the main tank body has sealing door, be connected with the baffle on the inner wall of the main tank body, one side of baffle is connected with the backup pad, the top of backup pad is connected with the one end of spring, the other end of spring is connected with the bottom of stripper plate, the stripper plate is located the bottom of spring one side and is connected with the one end of gag lever post, the other end of gag lever post passes backup pad and limiting plate in proper order and extends to the bottom of limiting plate, the one end of limiting plate is passed the baffle and is connected with one side of connecting plate, the top at the siren body is connected to the connecting plate. The utility model discloses a setting of backup pad, spring, stripper plate, gag lever post and limiting plate makes alarm convenient and fast more in the installation, has reduced the installation time of siren like this, has improved the work efficiency of installation siren.