In order to carry out the modal analysis of the exhaust system，the modal parameters of a car exhaust system at 0-200Hz are obtained by finite element calculation and experimental measurement respectively. By comparison，it is found that the errors of natural frequencies of each order obtained by the two methods are less than 10%，and the mode shapes are identical，which proves that the finite element model of exhaust system is correct and reliable. Afterwards，four hangers locations of exhaust system are preliminarily determined by means of ADDOFD method．In order to validate whether the hanger location is reasonable or not，establishing a finite element model of exhaust system including power assembly for static simulation calculation of hanger lugs，it is found that the deformation of two hanger lugs exceeds the engineering limit of 3.5mm．After adding one hanger for optimization，the static deformation and stress improvement percentage of the five hanger lugs are more than 13%．The research method has certain reference value for the early development and the selection of hanger location of a car exhaust system.