Abstract: Based on the aerial photos of sea ice floes in the marginal ice zone(MIZ)of Prydz bay near 69°00'S、76°24'E taken during the 21^st Chinese. Antarctic Research Expedition(CHINARE2004),the image processing techniques are employed to extract many geometric parameters of ice floes in the MIZ.The variations of floe size parameters,such as area and mean caliper diameter(MCD)with increasing distance to open water are obtained. And according to the variation trend,the whole MIZ is divided into three zones made up of floes of quite different characterist ics:edge zone,transition zone and internal zone Such division is closely associated with the wave attenuation in the MIZ.The variation of floe roundness reveals that the floes in the transition zone receive most sufficient abrasion because of significant collisions in there Moreover,an improved power law function and a Weibull function fit the cumulative distribution of floe size,and the calculated parameters contained in the two functions give nice descriptions of the evolution of floe size distribution in the MIZ.The parameter L_r increases with the distance to open water,revealing the increase of max floe size with wave attenuation Scale parameter L₀ increases with the distance to open water,showing the increase of average floe size and the proportion of large floes.The distribution dimension D decreases with the distance to open water,displaying the weakening of confinement degree as ice breakup Shape parameter decreases with the distance to open water,disclosing the widening range of floe size distribution.