The phase transition of perovskite thin films is inherently rapid and highly sensitive to multiple factors. Fluid dynamics has emerged as a powerful framework for elucidating the crystallization and phase transformation processes in perovskites. It governs solute transport, energy dissipation pathways, and mass transfer efficiency, thereby exerting a significant influence on nucleation behavior and crystal growth dynamics. These factors are critical for optimizing film morphology and enhancing device performance in large-area perovskite modules. In this perspective, we first explore the regulatory role of fluid dynamics across distinct phase transition stages and the underlying mechanisms. Then, its practical value in improving film uniformity and optoelectronic performance is examined, with particular emphasis on controlling crystal growth orientation and enhancing structural consistency. Such regulation is considered beneficial for improving device performance and ensuring long-term operational stability under ISOS protocols. Finally, we outline emerging opportunities in solution flow control, crystallization induction, defect passivation, and structural design. These insights offer promising directions for addressing key challenges in stability and scalable fabrication, thereby advancing the development of low-cost, manufacturable perovskite technologies.