Abstract: The hybrid method based on large eddy simulation and acoustic analogy is used to predict two-dimensional far field noise induced by flow around a cylinder at different Reynolds number.The simulation results are in agreement with experimental data.Based on the prediction results,the characteristic of the acoustic field,the effect of flow oscillation on noise levels and the noise radiation are studied;the noise reduction methods are searched.The results validate that the overall sound pressure level of the receiver increases with the increase of Reynolds number;the oscillation law of the flow has influence on the sound pressure level;the noise radiation directivity is similar to the radiation directivity of a dipole source;reducing Reynolds number or unsteady force induced by detached eddy can reduce the noise induced by flow around a cylinder.