Abstract: Aptamers are single-stranded oligonucleotide ligands that can bind to their targets with high specificity and affinity. Aptamers are selected from a single-stranded oligonucleotide library by the systematic evolution of ligands using the exponential enrichment technique. The aptamers against tumor biomarkers can be used to establish new specific and sensitive approaches for the biomarker assay. These aptamers can also be used to capture tumor cells in the blood for related analysis, deliver drugs to target tumors for targeted chemotherapy, and implement tumor biotherapy by biofunctionally blocking their targets. The selection and application of aptamers against tumor biomarkers are considered a new field in tumor research.