To effectively monitor the inclination angle of transmission towers and ensure the safety and reliability of the power grid operation，a high-precision transmission tower inclination angle monitoring system based on an optoelectronic oscillator（OEO）is proposed and experimentally verified. First，the inclination angle sensor model is theoretically analyzed and established based on the optical fiber stretch length，mapping the inclination angle information to the oscillation frequency change of the OEO by using the relationship between the OEO oscillation frequency and the cavity length. Next，the oscillation frequency is divided by the frequency divider，and then the Field Programmable Gate Array（FPGA）is used to perform real-time calculations of the inclination angle parameters，achieving real-time monitoring of the transmission tower inclination angle. Finally，the feasibility of the theory is verified through experiments，achieving measurements within the range of 10°，with a monitoring precision of 0.011′，a resolution of 0.003 6″，and a system real-time processing response time as low as 50 ms. The feasibility and effectiveness of this system for real-time monitoring of transmission tower inclination angles are thus verified.