With the continuous increase in voltage levels in power systems, 330 kV cables are increasingly utilized in urban power grids. During operation, cables accumulate heat continually, and excessive temperature rise can lead to accelerated aging of cable insulation materials, decreased mechanical properties, and even severe faults such as insulation breakdown, posing a threat to the safe and stable operation of the power grid. Accurate calculation and prediction of cable temperature rise are of great significance for reasonably determining cable ampacity, optimizing cable operation modes, extending cable service life, and preventing cable faults. They are crucial steps in ensuring the safety, stability, and economic operation of the power grid. This paper focuses on 330 kV cables and establishes a cable temperature rise calculation model based on the finite element method, comprehensively considering factors such as conductor resistivity, thermal conductivity of insulation materials, cable burial depth, and external ambient temperature that affect cable temperature rise. Through simulation calculations, the temperature distribution of various parts of the cable, including the conductor, insulation layer, and metallic sheath, under different load conditions is obtained. A large-current temperature rise test system for 330 kV cables laid in duct banks is set up to validate the simulation results. Test results indicate that the simulation calculations align well with the experimental results, with a maximum error of less than 5%, verifying the accuracy and effectiveness of the established model. The research findings of this paper can provide theoretical basis and technical support for the selection, operation maintenance, and life assessment of 330 kV cables, and are of great significance for improving the safety and economy of cable operation.