Abstract: MIBS is a lightweight block cipher based on Feistel structure, suitable for RFID, wireless sensors and other resource-constrained hardware environment. Differential fault attack is a kind of side channel analysis method which is effective for hardware cipher algorithms. The key recovery is carried out by the relationship of the related-key involved both in the inserting fault and the fault propagation. By using the difference nonuniformity of S-box, through the establishment of the relationship among plaintext difference, ciphertext difference and candidate input value, injecting two faults in the last round of MIBS, the last round key can be quickly recovered, and then all the keys. The idea of the attack is general, and it is generally applicable for the lightweight ciphers based on Feistel structure.