To address the issue of insufficient insulation margin caused by electric field distortion at the gas-solid interface of the DC GIS cable termination on offshore wind power converter platforms

this paper proposes a structural optimization method for epoxy bushing applicable to ±550 kV GIS cable termination. First

the electric field distribution at the gas-solid interface under different temperature gradients is analyzed. Then

an electric field optimization model under large temperature differences is constructed

and the outer structural profile of the epoxy bushing is parametrically modeled. To overcome the limitations of time-consuming finite element calculations and the insufficient accuracy of traditional surrogate models

this paper proposes a two-layer stacking ensemble surrogate model to capture the mapping relationship between structural parameters and the objective function. The upper layer selects the optimal learner configuration

while the lower layer optimizes the corresponding hyperparameters. An Improved Sparrow Search Algorithm (ISSA) is employed in conjunction with the trained surrogate model for iteratively optimizing and obtaining the optimal structural parameters. Under large temperature difference DC steady-state conditions

the optimized structure achieves a 12.8% reduction in maximum electric field intensity and a 15% increase in initial discharge voltage. In addition

the proposed solution meets mechanical performance design requirements. The optimization design method presented in this paper is expected to provide a valuable reference for the structural design of epoxy bushings in DC GIS cable termination for offshore applications.