Abstract: The response of the towed line array to the noise from the tow ship is investigated by normal mode modeling and computer simulation in this paper. The phenomenon that the maximum output of the towed line array is away from the endfire direction towards the tow ship is explained. The result is important for the understanding of the phenomenon and also for the application research concerning the suppression of the noise from the tow ship as well as adequate application of towed array techniques in shallow water.