Abstract: The security of the block cipher MIBS against integral attack was analyzed and a 5-round distinguisher of MIBS was founded. Considering the equivalent structure of Feistel structure and the relation of master key and round key in the key expansion algorithm of MIBS, it applied integral attack to 10 rounds of MIBS and gave the attack algorithm. The data and time complexities of 10 round attack on MIBS-64 are 228 and 252.7 respectively. The data and time complexities of 10 round attack on MIBS-80 are 228.2 and 253.2 respectively. These results demonstrate that integral attack on 10-round MIBS is no immunity, both rounds and data complexity of this integral attack are better than the integral attack existing.