This study focuses on the detection of dimethyl methylphosphonate （DMMP）, a simulant of sarin, and presents the development of a graphene oxide（GO）-based surface acoustic wave（SAW） gas sensor for DMMP detection. The sensor is fabricated using semiconductor planar technology, wherein a metal aluminum transducer is deposited onto a quartz substrate to form a delay line structure. Additionally, a GO gas-sensitive film is applied along the acoustic wave propagation path using a drop-coating method. At room temperature, the SAW sensor demonstrates high sensitivity （0.6 mV/ppm） and a rapid response time （T₉₀ = 45 s） over a DMMP concentration range of 1 ppm to 40 ppm. Furthermore, the sensor exhibits good stability, with negligible performance degradation observed after two weeks of storage.