In　this　paper,realized　methods　of　distributed　optical　fiber　sensing　technique　and　a　kind　of　sensing　technique　based　on　the　Sagnac　optical　interferometer　theory　were　summarized.　The　relationship　between　leakage　position　and　phase　difference　(phase　noise　and　receiving　power)　microbend　loss　is　analyzed　and　simulated.　We　acquire　that　receiving　power＇s　increment　will　lead　to　phase　noise＇s　decrement　When　faced　with　different　wavelengths,　phase　noise　differ　Tor　the　leakage　position　and　phase　difference,when　wavelength　is　1550nm,　its　resolving　power　can　reach　0.148rad/m.