Observed hydrographic data from World Ocean Database 2013 and Chinese National Arctic Research Expedition are used to document oceanic changes in the Chukchi Sea affected by global warming and sea ice retreat. Results show obvious warming and freshening signals in the eastern Chukchi Sea since 1974. Significant warming in surface occupies most of the eastern Chukchi Sea except for the central channel south of 69°N due to effect of the Pacific inflow. Warming rate in northern Chukchi Sea is much larger than the southern part. For the water below 30m, changes in temperature and salinity along the whole central channel are insignificant, while significant warming and freshening signals are observed in the Alaska Coastal Water. Analysis of a multi-year observed meridional section along 169°W shows a deeper and weaker thermocline after 1997 with large warming and freshening located in the thermocline (15-25m). The data also show evidence of changes in characteristics of various water masses in the Chukchi Sea.