Abstract: Focusing on the challenge of real-time accurate monitoring for burial depth of 110 kV single-core submarine cables, the typical HYJQ41 64/110 kV 1×300 mm² submarine cable was used as the research prototype to explore burial depth prediction approach and thermal circuit analysis based on distributed fiber-optic temperature sensing. An electro-magnetic-thermal multi-physics coupled finite element model was established, reliability of which was verified via mesh independence examination and benchmarking in accordance with IEC 60287-1-1: 2023. Steady-state numerical simulations under diversified operating conditions were implemented to quantitatively characterize impacts of ampacity and ambient temperature on the correlation between optical fiber temperature and burial depth, and a generalized multivariate-coupled inversion model for burial depth was subsequently deduced through nonlinear fitting. Thermophysical implications of the fitting parameters were elaborated on the basis of equivalent thermal circuit method, with systematic error validation conducted synchronously. Results manifested a remarkable logarithmic correlation between optical fiber temperature and burial depth. Ampacity governed temperature sensitivity to burial depth fluctuations, while ambient temperature exerted a linear impact on reference temperature of the optical fiber. The proposed generalized inversion model delivered an average relative error of less than 8% within the experimental scope, and relative deviations between theoretical results derived from thermal circuit method and simulation-fitted data were both below 5%. The established approach could enable real-time burial depth inversion exclusively relying on the built-in optical fibers of submarine cables without additional hardware modification, thereby providing theoretical fundamentals and technical solutions for secure operation and maintenance of submarine cable systems.