Abstract: The distribution and variation of submerged macrophyte, playing an important role in lake ecosystem, is an good indicator for assessing the effect of water environment comprehensive management and restoration. By reviewing the shortcomings of the existing methods for submerged macrophyte investigation and introducing the functions and application of DT-X echosounder, the possible technical difficulties of the device application in submerged macrophyte investigation of Taihu Lake are analyzed. The device was applied experimentally in several selected cross-sections. The application shows that the investigation result is basically consistent with that of manual investigation, so the device has a broad prospect in submerged macrophyte investigation of lakes.