Abstract: MicroRNA（miRNA） is a group of tiny RNA molecules which wildly exists in nature world. It was once considered as meaningless fragments generated during RNA maturation. However， in recent years， miRNA was found to be pivotal molecules in a variety of physiological and pathological processes in human beings. As a representative member of miRNA， miR-155 played important regulatory roles in the occurrence and progression of a large number of tumors. In this article， progress in the relationship between miR-155 and digestive system neoplasms was reviewed.