Abstract: Due　to 　the 　tidal 　effectsea 　ice 　in　Polar　Regions　moves　verticall y　alon g　with　the 　sea 　level．The　elevation 　of 　the 　sea 　ices　upper 　surface 　can　be　detected　by　a　GPS　receiverand　sea 　level 　can　be measured　by　tide 　observations．Thereuponif 　we　can　provide 　the 　thickness 　of 　the 　snow　cover 　over 　the sea 　iceand　the　densities　of 　snow　and　sea 　icethenaccording　to 　the　princi ple 　of 　hydrostatic　balance thickness 　of 　the 　sea 　ice 　can　be　derived　by　a　combination　of 　the　GPS　and　tide 　observations．The　experiment　conducted　by　the 　28th　Chinese　National　Antarctic　Expedition　at 　Zhongshan　Station 　in　Antarctica during　September 　222012to　November　9indicates　that 　the 　sea 　ice 　thickness 　can　be 　estimated 　in 　centimeterlevel 　accurac y　by　this 　app roach．Compares 　to 　the　measurements　made　by　drillin g　holesthe　maximum　difference 　is 　8．9centimetersthe 　root　mean　square　of 　the 　different 　values 　is 　5．4centimeters．