Abstract: Using large eddy simulation method and FW-H acoustic model, the flow field, surface pressure fluctuation and broadband noise radiation of a Clark-Y airfoil were analyzed under low Mach number flow conditions. Simultaneously, the spectrum of blade surface pressure was compared with that of the far field sound pressure. Results show that the near wall separation vortex has a correlation with the blade surface pressure fluctuation; each pressure fluctuation is related with a pulsating vortex. The radiation capacity at far field of separation vortex is very small, and the broadband noise mainly comes from the pressure fluctuation caused by both the leading edge impingement and the trailing edge separation; the radiation capacity at leading edge is larger than at trailing edge.