The Arctic Ocean is a very important component of the global climate system due to its geographical location, its interaction with the lower latitude atmosphere has significant impact on regional climate and weather patterns, its water exchange with both the Pacific Ocean and the Atlantic Ocean especially the latter, modulates the Atlantic overturning circulation, the formation of deep water and then large scale circulation of the global ocean. Recently, the Arctic Ocean is undergoing unprecedented air temperature increasing (the “Arctic amplification”), sea ice decline, freshening of the surface layer and warming events which are tightly connected with a shift in ocean circulation and physical conditions of the ocean. Here, we will analyze the sea level variation of the Arctic Ocean in the past 3 decades to understand the recent change occurring in this region, basing on a 4.5km resolution Arctic Ocean simulation with the global multi-resolution model FESOM (Finite Element Sea ice-Ocean Model). The model is developed by Alfred Wegener Institute for Polar and Marine Research (AWI), it employs unstructured triangular meshes and allows for variable resolution without traditional nesting and considers the dynamic–thermodynamic processes of the sea ice. The simulation is conducted using the latest version of the model FESOM1.4, has 1° nominal horizontal resolution in most parts of the world’s ocean; the resolution is tripled in the equatorial band and is set to about 24 km north of 45°N and further increased to 4.5 km inside the Arctic Ocean. The model is forced by the JRA-55 data set including both the atmospheric forcing and river runoff at an interval of 3 hours from 1958 to 2016. Monthly output of sea surface height(SSH) is validated using both satellite altimeter (1993-2016) and long term tide gauge observations (1958-2016) and is compared with two reanalysis data sets (SODA and ORAS3) and it is found that FESOM made a much better hindcast of the sea level variation in the Arctic Ocean than the other two reanalysis products. Basing on the output of the last 30 years of the simulation, we will analyze the inter-annual sea level variation and long term sea level trend of the Arctic Ocean, to interpret the connection between the variations of sea level and thermohaline structure and ocean circulation for a better understanding of the changes occurred in the Arctic Ocean in the past 3 decades.