The utility model provides a be used for inside conflagration early warning of cable pit and automatic fireplug which includes data display collection module, alarm module, sensor group, aerosol put out a fire module, communication module and fireplug body. The utility model provides a fireplug body has functions such as rain -proof, dustproof, lightning protection, fireplug casing upper portion is for showing and alarm device, and there is the access door fireplug side to make things convenient for the maintenance of fireplug to maintain, the front of fireplug has the button of switching, andthe display parameter who is used for controlling display device switches between gas strength and temperature, and the access door has carried out special processing at the commissure to guarantee that the commissure is waterproof, dustproof, consider that summer temperature in high, winter is low, the utility model discloses set for different warnings and put out a fire data combinations temperature and mist concentration, effectually prevented wrong report, the production of failing to report, system power supply passes through reliability design, has ensured the power supply system's of fireplug high reliability and high stability.