The positioning technology based on the time difference of arrival (TDOA) of the acoustic sensor array has gained more attention because of its relative ease of implementation. Since linear frequency modulation (LFM) signal has good correlation characteristics, it is widely used for frame synchronization in underwater acoustic(UWA) communication. However, due to the characteristics of large propagation delay, serious multipath effects and dynamic sound speed, existing TDOA methods experience serious ranging errors in shallow water area. In this paper, we propose a correction mechanism based on passive positioning of shallow water targets, which corrects the sound velocity and estimates multipath effects that cause ranging errors to obtain more accurate target position information. Through the field test results in shallow water, we prove the effectiveness of the proposed mechanism.