Abstract: A high-precision optical fiber axial strain sensing system combined with optoelectronic oscillator (OEO), using a section of standard single-mode fiber as the sensing head, is proposed and experimentally demonstrated. In the proposed scheme, the mode selection in the OEO cavity is achieved via a single-passband microwave photonic filter which is realized by an amplified spontaneous emission (ASE) light source, a dual-output Mach-Zehnder electro-optic intensity modulator (DOMZM), and a Mach-Zehnder interferometer (MZI) involving two sections of optical fiber with different length. Through applying axial strain to either arm of the MZI, the length difference between the two arms of the MZI varies. Hence, the frequency of the generated microwave signal in the OEO varies, which is used for axial strain sensing. In the experiment, when the axial strain is applied to the longer fiber, the sensitivity and the linearity are measured to be 4.67121×10⁻⁴ GHz/με and 0.99895, respectively. When the axial strain is applied to the shorter fiber, the sensitivity and the linearity are measured to be −4.48388×10⁻⁴ GHz/με and 0.99841, respectively.