The invention relates to the field of fire fighting equipment, and aims to provide a fire extinguisher. The fire extinguisher comprises a shell, a fire extinguishing agent, a gas generator, a temperature sensing plate, a sprayer, a containing hole, an ejection plate, a compressed spring, a plurality of through holes and a fusible alloy ring, wherein the lower end of the shell is provided with an outlet hole; the fire extinguishing agent is contained in the shell; the gas generator is arranged inside the shell, the lower end of the gas generator is provided with a trigger probe, and the side wall of the gas generator is provided with a plurality of upper gas outlet nozzles; the upper end of the temperature sensing plate is connected with the lower end of the shell, and the lower end of the temperature sensing plate is provided with an outlet pipe; the sprayer is connected with the outlet pipe; the containing hole is formed in the upper end of the temperature sensing plate, and the lower end of the containing hole communicates with an inner hole of the outlet pipe; the ejection plate is arranged in the containing hole, and the upper end of the ejection plate is provided with an ejection rod opposite to the trigger probe; the two ends of the compressed spring abut against the lower end of the ejection plate and the bottom face of the containing hole correspondingly; the multiple through holes are formed in the ejection plate and are circumferentially distributed along the ejection rod; and the fusible alloy is arranged outside the ejection rod in a sleeving mode, the outer side wall of the fusible alloy ring is connected with the side wall of the containing hole, and the lower end of the fusible alloy ring presses the upper end of the ejection plate. The fire extinguisher can be automatically started for putting out a fire at unattended operation places, and the spraying range of the fire extinguishing agent is wide.