Abstract: This paper attempts to summarize the recent progress of the studies of paleoclimate and sea level changes and their sedimentary records during the period of the marine oxygen isotopic stage 3 (MIS 3). The paleoclimaic change during the MIS 3 is an important topic of the global paleoclimate research, since some of its characteristics are similar to those of today. All the evidence from ice cores and oceanic and terrestrial deposits indicates that the Earth's climate system experienced a series of rapid changes during that period on centennial to millennial timescales. However, the causes, mechanisms and impacts of these abrupt climatic events remain uncertain. The sea levels in MIS 3 estimated from marine oxygen isotopes, coral reef terraces and terrigenous clastic sedimentary records are quite deviated. The majority of the researchers believes that the sea level fluctuation during that period were in a range of -50 to -90 m, but another school suggests that it was -15 to-20 m only, much less than the previous estimation. In-depth researches of paleoclimate and sea-level changes in the future are required based on more high-resolution evidence from various channels in a global scope.