As a key component in the subsea production system for oil and gas exploitation, a marine umbilical consists of optical cables, electrical cables, steel tubes, and filler bodies. The difference of materials and dimensions between the components leads to a great difference in their mechanical properties, and the different layouts cause a large gap in the performance of an umbilical. Considering the compactness, balance and heat source dispersion of the cross-section, a multi-objective optimization model is established in this paper. Based on the quasi-physical algorithm, the layout design of cross-section of an umbilical containing equal-diameter components is carried out. Due to the number of functional components, the optimized cross-section will have large gap. In order to meet the requirement of dense cross-sectional layout in the umbilical cable design specification, a strategy for automatically filling filler bodies based on image recognition is introduced and combined with the layout optimization process. Finally, taking an umbilical as an example, after obtaining the optimal layout through the quasi-physical algorithm, the filling strategy is utilized to complete the design of cross-sectional filler bodies. The validity of the algorithm is verified by comparing with the initial cross-sectional layout, which proves it is an effective reference for the design of cross-sectional filler bodies of umbilicals.