<p>This paper presents a fluid–solid coupling model established using Fluent software, which incorporates the molten pool and casting rolls based on the characteristics of the top side-pouring twin-roll casting process. A finite element − cellular automata model has been developed by integrating finite element analysis and cellular automata methods, enabling numerical simulation of the temperature fields of the casting rolls and molten pool, as well as visualization of the solidified microstructure. The simulation outcomes demonstrate a high degree of consistency with the experimental results. The research findings indicate that, with the decrease in superheat, the increase in the number of cooling water holes, and the reduction in the distance between cooling water holes and the roll surface, the roll surface temperature decreases, the solidification point of the molten pool shifts upwards, and the average grain size of the solidified microstructure exhibits a refinement trend.</p>