The invention provides a highly integrated fiber optic interferometer. The highly integrated fiber optic interferometer consists of a light source, a single-mode single-core input fiber, a first split-light cone coupling region, a single-mode dual-core sensing fiber, a combined light cone coupling region, a single-mode single-core transmission fiber, a second split-light cone coupling region, anda single-mode dual-core output fiber, and a photo-detecting chip. The highly integrated fiber optic interferometer uses a photo-detecting chip designed in an integrated circuit process that matches the position and shape of the output fiber core to perform collection, photoelectric conversion, and process on the output of the interference light. The highly integrated fiber optic interferometer greatly increases the integration of the overall system, reduces the size of the interferometer system, reduces the complexity of the system, and increases the reliability. The highly integrated fiber optic interferometer can be used for accurate measurement and real-time monitoring of various physical quantities such as temperature, pressure, and magnetic force, and can be widely used as a sensor node in the sensor network and the Internet of Things system.