Quantum dot-encoded beads as a new type of fluorescent labels exhibit significant advantages over common organic dyes, such as narrow, strong and tunable emissions, excellent photo stability, good versatility in structure and component, and simplicity for excitation of multiple nanocrystals. These features lead to the great potential of the beads in the fields of ultrasensitive detections, clinical diagnostics, as well as molecular imaging. This report will briefly review the fabrication and optical properties of the beads based on recent papers and patents. The applications of the beads in ultrasensitive detections are also discussed. The systematic introduction from basic studies to practical applications would give us a comprehensive and clear view about this field, disclose the current challenges, and promote their future developments.