Abstract: In 2011 and 2012, with the Haiyang-6 as the carrier, EM122 multibeam bathymetric system was used to carry out the full coverage depth measurement in the Challenger Deep, the deepest point in the Mariana Trench. Detail bathymetric data were obtained from the region. It was revealed that the trench extended in an east-west direction and the geomorphological features are different between the two sides of the trench, indicating the differentiation of the secondary tectonic activities. There are three depressions in the Challenger Deep, with the western depression as the deepest. The depth of the central point(142° 12.14' E,11° 19.92' N) is 10 917 meters, which, in fact, is the deepest point in the Mariana Trench.