By using the satellite total ozone data of TOMS(Total Ozone Mapping Spectrometer) and OMI(Ozone Monitoring Instrument) from 1978 to 2011, the ozone profile data of MSL(Microwave Limb Sounder) in 2011 and NCEP/NCAR reanalysis meteorological data, the total ozone (TO) seasonal and interannual variations over the Polar Regions are studied.The unusual phenomenon of serious Arctic ozone depletion in later winter and early spring of 2010/2011 is emphatically analyzed, and causes of the phenomenon are explored.Results show that there is a climatic low ozone center over Antarctic through the whole year.However, Arctic ozone decreases from spring to summer (from April to August), reaches the minimum in autumn (October) and recovers rapidly in winter (from November to next February).The differences of the TO seasonal variation are due to the polar circulations and the temperatures diversity in the Polar Regions.The interannual variation of annual averaged TO presents a decline trend, with maximum monthly deviations in spring time in the Polar Regions.In recent 30 years, the unusual low TO values in spring time (from March to April) over Arctic occurred in 1997 and 2011 with 355 DU and 361 DU, respectively.But there are no obviously trends in recent 10 years over the Polar Regions.In the early spring of 2011, an unusual low TO occurred and lasted about one month from middle of March to middle of April over Arctic, which corresponded well with extremely low temperature in the stratosphere in winter and spring 2010/2011.