High-throughput screening is an indispensable technology in drug discovery, cancer therapy, and disease diagnosis, and it could greatly reduce time cost, reagent consumption, and labor expense. Here, four high-throughput screening methods with high sensitivity and accessibility are discussed in detail. Fluorescence, DNA, heavy metal, and nonmetal isotope barcodes, which generally label antibodies, proteins, and saccharides to identify cells, are detected by flow cytometry, second-generation DNA sequencing, mass cytometry, and second-ion mass spectrometry, respectively. Encoding binary information in barcodes, labeling individual cells by barcodes, performing the characterization of cells together, and identifying the result belonging to individual cells via barcodes are the main steps for high-throughput screening. Applications of the four digital barcodes in high-throughput screening for both in vitro and in vivo tests are described in detail, and their advantages and disadvantages are also summarized. High-throughput screening has provided a powerful platform widely accessible for multidisciplinary studies and has greatly sped up the progress of drug discovery, disease diagnosis, and cancer therapy.