Under the long-term influence of external incentives such as ocean current scour, human activities and geological movements, the buried depth of submarine cables is prone to continuous changes, which leads to a series of serious problems such as a sharp increase in the failure rate of submarine cables and a sharp decline in load capacity. This paper takes 35 kV photoelectric composite three-core submarine cable as the main research object, uses the finite element method to simulate the temperature field of submarine cable under different ambient temperatures, different burial depths and different carrying rates, establishes the relationship curve between cable core temperature and buried depth under different ambient temperatures, and the relationship curve between cable core temperature and buried depth under different ambient temperatures, and fit the corresponding relationship formula. The general formula of the relationship equation for real-time prediction of submarine cable buried depth was integrated. Finally, by using the multi-source data of the actual project monitoring, the buried depth and change trend of submarine cable are predicted in real time through the general formula. At the same time, combined with the measured value of submarine cable disturbance energy and submarine cable buried depth, it is verified that the prediction method is not only feasible and correct, but also has high prediction accuracy.