Abstract: Based on the CTD station observational data of five Arctic consecutive voyages of CHINARE (Chinese National Arctic Research Expedition) in the Near Strait from 2003 to 2014, the multi-year profile structure, characteristics of pycnocline and the “liquid seafloor” in the strait in summer are studied with characteristic statistics and time series analysis. The results show that the vertical stratification in the Near Strait is very significant in summer, and the density and salinity profiles both show a 4-layer structure, while the temperature profile shows a 4-layer or 5-layer structure. All the 5 voyages data exhibit a cline structure, in which the thermocline is most significant, followed by the pycnocline then the halocline. The “submarine cliffs” were not found in the strait, while the “liquid seafloor” is prominent. The study indicates that vertical stratification in the strait is controlled by local sea surface heating in summer and strong vertical convective mixing in upstream sea area in previous winter. Sea surface heating and residual winter water play a key role in the cline structure characteristics. This study is of great reference value for deeper understanding of marine environment, climate change, ecosystems, and resource utilization around the Near Strait.