<p>To reduce welding deformation and welding stress during the automatic welding of obliquely intersecting large-diameter curved penetration components in shipbuilding and offshore engineering applications, and thereby improve the welding quality of intersection-line weld seams, a numerical optimization study on segmented and multi-layer multi-pass welding sequences and process parameters was conducted. First, based on the established welding model, multi-layer multi-pass welding trajectory equations for obliquely intersecting curved penetration components were developed. Subsequently, numerical simulations of four different welding sequences were carried out for obliquely intersecting curved penetration models with three representative sizes. Finally, welding process parameters were numerically optimized for the three component sizes under the optimal welding sequence. The optimization results indicate that the fully cross-symmetric welding sequence can reduce welding deformation and welding stress by an average of 4.80% and 4.14%, respectively. Numerical investigations of welding process parameters under the optimal sequence show that the welding current needs to be increased with increasing wall thickness of both the curved components and the penetration component. In addition, welding deformation and welding stress are mainly influenced by the vertical welding segment. With increasing wall thickness, the influence of the vertical welding segment gradually decreases, whereas the influence of the overhead and horizontal welding segments increases progressively.</p>