YAP1(Yes-associated protein 1)is a molecular of Hippo pathway. In early studies, researchers found that YAP1 was inactive when Hippo pathway was well functional. When some molecules mutated in Hippo pathway, YAP1 was hyperactivated. Hyperactivated YAP1 could promote cell proliferation, metastasis, cell survival and maintain the activity of stem cell. Because hyperactivated YAP1 can promote the occurrence and progress of tumor, YAP1 was defined as an oncoprotein. Recently, researchers found that YAP1 variants were associated with survival rates of small-cell lung cancer patients. YAP1 interacted with catenin and Kras to regulate infiltration and metastasis of cancer cell. And some microRNAs could interact with YAP1. Based on the function of YAP1, we can find some therapeutic strategies and targets for cancer treatment. This paper summarize the studies of YAP1 and provide some evidence for basic and clinical research of cancer therapy.