A distributed acoustic sensing system based on an optical neural network and an all-optical integration method are provided. The distributed acoustic sensing system based on an optical neural network includes: a distributed acoustic sensing (DAS) optical path integrated part, an external connection part, and an integrated signal processing chip. The provided combines an integrated optical delay line, a tri-port analogous detection structure and a pure optical neural network module to achieve all-optical integration of the DAS sensing system and signal processing by a pure optical method, which has the advantages of reducing photoelectric conversion, enhancing parallel processing capabilities, increasing processing speed, reducing energy consumption, improving system stability, and simplifying system architecture.