Abstract: Uniaxial compressive strength tests were conducted for polycrystalline ice with average grain sizes of 0 5,1,2,3,4 and 6 5mm at -5℃ and at the strain rate of 6μs -1 . It is found that the compressive strength of ice is very sensitive to the grain size and is directly proportional to the reciprocal of squre root of the grain size.And the failure strain decreases linearly with the increase of the grain size.