Abstract: Provided is a swim bladder bionic amphibious optical fiber ocean acoustic sensor, belonging to the field of optical fiber ocean sensors, consisting of a sound sensitive diaphragm, a diaphragm supporting shell, a section of coated optical fiber, a single-hole optical fiber sleeve and a single-mode optical fiber. An upper surface of the supporting shell is provided with two symmetrical overflow holes, and a structure includes a back cavity communicated with the overflow holes. A medium in the back cavity of the sensor may be replaced by inflating, deflating and filling water through the overflow holes, to achieve impedance matching with external environments. When the back cavity is inflated, the sensor serves as a fiber-optic microphone, and when the back cavity is deflated and filled with water, the sensor serves as a fiber-optic hydrophone. The working states could be switched flexibly to achieve a working mode like a swim bladder.