Biosensing platform is one of the branches of chemical sensing platform,which is sensitive to the biomolecules and can convert the concentration changes of biomolecules into electric signal for the sensing purpose.Among the various biosensing platforms,fluorescent nano-biosensing platforms have attracted widely attention due to their advantages of high sensitivity,good selectivity,operational simplicity,low cost,real-time monitoring,etc.In recent years,with the rapid development of nanotechnology,nanostructured materials(nanomaterials) exhibit some special advantages in the field of biosensing.Compared with the traditional materials,nanomaterials exhibit unique physical and chemical properties,such as optical,electrical,mechanical,catalytic and magnetic properties.As a novel type of multifunctional nanomaterials in nanoscience and nanotechnology,metal(e-g.,Au,Ag,Cu,and their alloys) nanoclusters(MNCs) are typically composed of several to dozens of metal atoms whose core sizes are usually below 2 nm.Benefiting from their unique properties of strong photoluminescence,facile preparation and surface functionalization,excellent biocompatibility,ultra-small size and low toxicity,MNCs have been applied in many fields such as energy catalysis,medical treatment,electronic devices and biosensing.Especially,they have extremely outstanding fluorescent properties of large Stokes shift,tunable fluorescence emission,high optical stability and fluorescence quantum yield,compared with the traditional fluorescent organic dyes,proteins,quantum dots and other fluorescent materials.Based on the above properties,MNCs have been widely used as fluorescent nanoprobes in the field of biosensing.In this review,the latest development of MNCs based fluorescent nano-biosensing platforms on the basis of various construction mechanisms were presented.The applications of MNCs in the field of sensing ions,biomolecules,pH and temperature were introduced.It is believed that this review could provide some novel insights and theoretical guidance to construct more prospective biosensors based on different designed sensing mechanisms.