Abstract: Based on the investigated data of sea ice physical processes during the Second Chinese National Arctic Research Expedition(CHINARE 2003)in the summer of 2003,the sea ice dynamical characteristics are analyzed and the parameters expressing these characteristics are given. From these parameters,the new findings are:(1)The ice density from investigation is lower than 2-3 tenths compared with that from NOAA Ice Chart,and the ice thickness in the summer is less than 2 m compared with the results invest igated during the First Chinese National Arctic Research Expedition in 1999(CHINARE 1999); (2)The standing deviation of ice bot om fluctuation is 3.8 times of that of the snow surface on the ice sheet and(3)the maxi mum speed of ice floe CHIS7 is 1300 m/h in rotation and oscil ation While the floe moves toward North-east,the rotation angle increases step by step with the maximum of 37.8,and while the floe moves toward South-east,its rotation angle decreases step by step. The oscil ation period of the floe is 12.45 h consistent with that of the inertia current at the same latitude,which shows the contribution of the inertia current to the ice floe movement.