Abstract: To analyze the influence of Solitary Internal Wave (SIW) on acoustic field interference pattern and thereby monitoring SIW,we adopt parabolic equation model to simulate the variation of received pulse sequence of single normal mode with internal wave position when broadband pulse signal propagates through SIWs,and the spatiotemporal interference characteristics and mechanism of the sequence are analyzed.The relationship between internal wave position and interference striation slope is derived based on coupled mode theory,and simulation results show that the relationship can be used to monitor the position of solitary internal waves precisely,with greatly improved precision and robustness compared with previous work.Furthermore,we also develop another method to estimate SIW position based on the periodicity over frequency of the single normal mode interference pattern,which has better real-time property than the first method.The SIW-normal mode interference relationship can be used for improving acoustic field localization,which has great value for oceanology,marine engineering,marine military and so on.Besides,the relationship can be expanded to detection of other local characteristic variation,like metal flaw detection and localization of dramatic variation of ocean bottom bathymetry.