In order to obtain the spatial directivity of ship radiated noise at far field in shallow water,a new method is presented to compute the corresponding sound field distribution at far field.Firstly the sound pressure data measured by hydrophone array at near field was used to obtain the equivalent intensity and positions of multi-pole structure model for ship radiated noise,then the spatial directivity of far field radiated noise is computed by normal modes.A comparison between simulation results of far field spatial directivity of ship noise obtained by this method and the result obtained from direct computation using assumed data of sound sources show that the method presented in this paper can give an acceptable spatial directivity of far field.