Fibroblast activation protein α (FAPα), a surface antigen especially expressed on carcinoma associated fibroblasts (CAFs), is involved in tumor cells growth, adhesion, invasion and metastasis for its dipeptidyl peptidase and collagenase activities. Over expression of FAPα on CAFs and its special endopeptidase activity represent a potential target for diagnosis and treatment of various carcinomas, making it feasible to be applied in oncogene therapy and immunotherapy of targeting tumor cells. This review focuses on the relationship between FAPα and tumor development, and summarizes a series of studies involving FAPα structure, enzyme activities as well as clinical diagnosis and therapy of malignant tumors.