Abstract: We apply impossible differential attacks to 8-round AES-256.With the key schedule considerations,based on the techniques of looking up differential tables and re-using the data,a new attack on impossible differential cryptanalysis of 8-round AES-256 was presented.It requires the data complexity of about 2105 chosen plaintexts,time complexity of about 2229.58 memory accesses,and memory complexity of about 287 bytes,which is better than the previous known cryptanalytic results on 8-round AES-256 in terms of the memory.