The invention discloses an excitation device for a life jacket, which comprises a main valve body connected with a compressed gas cylinder, and is characterized in that: the main valve body is provided with a thimble device used for jacking the compressed gas cylinder, an elastic device used for driving the thimble device to move, and a condition control device used for exciting the elastic device, wherein the condition control device comprises water soluble fixed sheet; when the condition control device is immersed into water, the fixed sheet is rapidly dissolved to excite the elastic device in 1 second, so that the thimble device jacks the compressed gas cylinder under the action of an elastic force of the elastic device to inflate the life jacket. The excitation device for the life jacket has the advantages of simple structure, high sensitivity, and safety and reliability.