Offshore photovoltaic has the advantages of not occupying land area, higher power generation efficiency and strong capacity expansion, etc. The development of offshore photovoltaic is an important way to achieve the “double carbon” goal. A integrated offshore photovoltaic system-suction foundation supported integrated offshore photovoltaic system was developed. The structure is first assembled in one piece at a land-based factory and then transported to the designated sea area via a transport vessel. During the towing process, its safety and stability are affected by the movement of the ship. A numerical simulation study on the towing stability of the integrated offshore photovoltaic system was conducted using the SACS software, aiming to simulate the influence of hull motion during towing on the structural deformation and component strength characteristics of the integrated system. The results show that, in terms of structural deformation during towing, the structural node offsets are at a low level during normal towing, and the maximum displacements in the transverse, longitudinal, and vertical directions account for only 0.96%, 1.7%, and 0.5%, respectively, which can show the stability of the structure under conventional towing conditions. However, under extreme towing maneuvering conditions, the maximum nodal offset of the integrated marine PV system is significantly affected by the multi-dimensional hull motion, with an increase of 39.6% in the transverse-swing direction, 15.4% in the longitudinal-swing direction, and 12.2% in the pendant-swing direction, which clearly demonstrates that extreme towing speeds can have a great negative impact on the structural stability. Therefore, the integrated offshore photovoltaic system should avoid extreme towing speeds during the towing process to improve the overall stability and safety of the structure.