Studies on the extreme events of ozone depletion in the polar region are many but studies on the ozone extreme events of ozone valley over the Tibetan Plateau(OVTP) are few and mainly focus on case analysis.Therefore,this paper defined the extreme and ordinary events of OVTP and analyzed their characteristics based on the ERA-interim daily reanalysis data from 1979 to 2016.Firstly,this paper selected the characteristic isolines of extreme(ordinary) strong and weak OVTP according to total column ozone(TCO) and zonal deviation of TCO (TCO^*) after plus or minus 1.96(1.29) standard deviation of TCO and TCO^*,respectively.Secondly,this paper defined the extreme strong OVTP with TCO ≤ 250 DU and TCO^* ≤ -55 DU,the ordinary strong OVTP with 250 DU* ≤ -40 DU,the ordinary weak OVTP with 285 DU* ≤ -6 DU,and the extreme weak OVTP with-6 DU* ≤ 0 DU.Then this paper analyzed the characteristics of the extreme and ordinary OVTP.The results as follows:1) Extreme strong OVTP frequently occurs in summer and autumn,and it appears most in October when the occurrence is up to 2.0%.Ordinary strong OVTP frequently occurs in spring and summer,with the most occurrences in July when the occurrence is up to 1.7%.Extreme weak OVTP frequently occurs in autumn and winter,with the most occurrences in December when the frequency is up to 3.8%.Ordinary weak OVTP frequently occurs in winter,with the most occurrences in January when the frequency is up to 2.0%.2) Trends of extreme OVTP are significant,while trends of ordinary OVTP are not significant.Extreme strong OVTP increased significantly with 0.004%·a^-1.Extreme weak OVTP decreased significantly with 0.015%·a^-1.3) Area and strength of extreme strong OVTP are the largest in autumn and reach the maxima in October,with 4.3×10⁵ km² and 1.5×10⁵ t.Area and strength of ordinary strong OVTP are the highest in summer and peak in July,with 1.7×10⁵ km² and 4.1×10³ t.Area and strength of extreme weak OVTP are small in spring and summer and reach the minima in April,with 3.2×10⁴ km² and 1.1×10² t.Area and strength of ordinary weak OVTP are small in spring,summer and autumn,and reach the minima in April (October),with 2.5×10⁴ km²and 68 t (2.2×10⁴ km² and 97 t).4) The significant trends of area and strength of extreme (ordinary) strong OVTP are 2.5×10² (4.5×10²) km²·a^-1and 2.5×10²(4.5) t·a^-1,respectively.On the other hand,the significant trends of area and strength of extreme (ordinary) weak OVTP are -1.7×10⁴ (-2.3×10³) km²·a^-1 and -7.0×10³ (-2.7×10²) t·a^-1.