Abstract: According to a simplified bottom model,the vertical directionality of ambient noise was calculated in shallow water,and geo-acoustic parameters were estimated subsequently.The image method and the normal mode method were used at larger and smaller angles,respectively.The simulation results of the vertical directionality were in good agreement with the K/I noise model.A segmentation inversion scheme was proposed based on the analysis of noise data in shallow water,and then the noise intensity calculated using inverted parameters coincided with measurements at the same site. It was demonstrated that this method could describe the effects of bottom reflection on the vertical directionality of ambient noise,though the simplified bottom model was used.In addition,it was convenient to analysis the noise filed for the accurate layered structure could be neglected.