Provided is a self-generating thermosensitive type aerosol fire extinguishing device, which is composed of a generator, a motion mechanism, a temperature sensing controlling element of shape memory alloys, a detonator, wires, an aerosol maker and a producer, wherein the temperature sensing controlling element of shape memory alloys is connected with the motion mechanism and configured as an action switch which controls the motion mechanism. When the environmental temperature achieves or exceeds the recovery temperature of shape memory alloys, the temperature sensing controlling element of shape memory alloys begins to work and generates a changeof shape, thereby striking a motion of the motion mechanism to cause the generator to work, the electric current produced by the generator is transported to the detonator via wires to stimulate the detonator to work, then the aerosol maker is fired by the detonator, and the producer has an inside reaction to produce the required smog for fire extinguishing. The invention has simple structure, is not dependent on batteries and external powers, and is safe and reliable with long service time.