This paper presents a numerical study on the shell-side flow noise characteristics of staggered straight tube bundle heat exchangers under varying inflow conditions. A three-dimensional numerical model of a compactly arranged staggered straight tube bundle heat exchanger was established. To validate the numerical model, a feasibility study using a cylindrical flow model was conducted. Subsequently, the large eddy simulation (LES) method was employed to investigate the unsteady shell-side flow field characteristics, and the vortex characteristics of the flow field were obtained based on the Q-criterion. Finally, the acoustic finite element method (FEM) was utilized to calculate and analyze the noise characteristics at the inlet and outlet positions of the heat exchanger shell side. The results show that the inflow angle has an influence on both the flow field and the acoustic field of the heat exchanger shell side. As the inflow angle increases, the flow stability decreases, horseshoe vortices replace boundary layer vortices, and the decrease in fluctuating pressure leads to a reduction in flow noise. Analysis of the sound pressure level spectrum indicates a line spectral characteristic at low frequencies, with high-frequency components experiencing rapid attenuation.