The failures of node are the common phenomena in the massive distributed storage system.To prevent the data loss,the system must solve the problem of self-repairing for failed nodes.Using regenerating codes,the data of failed nodes can be recovered without downloading the whole source file,so repairing bandwidth can be effectively saved.This paper presents an exact-repair minimum bandwidth regeneration code (ER-MBR) by using Cauchy matrix as coding matrix.ER-MBR can exactly repair the failed nodes.The whole process of coding,decoding and node repairing is demonstrated in the finite fields by an instance.Theoretical analysis and simulation experiments prove that by using Cauchy matrix as coding matrix,the operation efficiency of this algorithm is better than that of using Vandermonde matrix or random matrix.