Abstract: MicroRNAs(miRNAs) are involved in the degradation of messenger RNAs(mRNAs) or translation inhibition by binding to the 3'-UTR of target mRNAs. Accumulated evidences have shown that miRNAs play crucial roles in cell proliferation, differentiation, development and apoptosis, etc. Also, miRNAs play important roles in tumorigenesis and tumor development by acting as oncogenes or tumor suppressor genes. Increasing studies have shown that microRNA-135(miR-135) is closely related to the occurrence of cancer. Therefore, this paper will review the mechanisms of miR-135 involving in tumor cell proliferation, apoptosis,invasion, metastasis, drug-resistance and prognosis. Hopefully it is useful to the early diagnosis, treatment and prognosis of tumor.