The invention relates to an automatic fire extinguishing device, and relates to a small automatic household fire extinguisher which is suitable for family kitchens and the like which easily cause fire, and belongs to the field of fire protection. The automatic fire extinguisher mainly comprises a fire detection device and a fire extinguishment mechanical response device. The fire detection device comprises a smoke detector, a temperature detector and a singlechip; the fire extinguishment mechanical response device comprises a gas storage box, a dry powder box and a dry powder box opening device. The small automatic household fire extinguisher has the advantages that when fire happens, smoke and temperature information can be detected within the first time, and a speaker and the gas storage box are instantly opened, so that an immediate alarm is realized and dry powder is sprayed for extinguishing fire.