Abstract: An indirect boundary element method for studying the sound field generated by monopole in a finite duct with flow was presented.Here,the region was divided into two single-connected regions bounded by duct and duct end facets.Taking the potential source as unknowns,a unified matrix equation was obtained through the pressure and velocity continuum condition at the duct end facets.Then the sound field,both interior and exterior to the duct,was determined from the potential source.The numerical results showed good agreements with Myer's benchmark data.The method could be easily extended to arbitrary shape of duct and complex source inside the duct.