The prediction of underwater noise requires accurate simulation of flow field fluctuations. The paper focuses on the SUBOFF submarine model and analyzes fluctuating pressure.  Dynamic Mode Decomposition (DMD) is used to study the correlation of pressure fluctuation and flow structures. Large eddy simulation (LES) method is employed to improve accuracy. Probes and arrays are set on the submarine's surface, allowing for analysis of linear spectrum, octave spectrum, and wavenumber-frequency spectrum. The results show that the resistance force can be predicted accurately with LES method, exhibiting an error of less than 1% compared to experiments. Fluctuating pressure within the submarine varies significantly across different zones. Convective velocity varies across different regions, decreasing from upstream to downstream. DMD results reveal that low-mode vortex structures dominate the flow field, characterized by larger scales. Conversely, high-mode structures exhibit smaller scales and lower energy ratios.