Compared　with　traditional　bulk　materials,　nano-multilayer　films　exhibit　unique　optical,　magnetic,　electrical,　mechanical　and　thermal　properties　due　to　their　small-size　effects,　surface　effects,　quantum　size　effects,　and　quantum　tunneling　effects.　Therefore,　nano-multilayer　films　have　been　widely　used　in　the　areas　of　optical　devices,　semiconductors,　electromagnetic　protection,　processing　and　manufacturing,　surface　protection　and　electronic　packaging　as　optical　absorbing　materials,　electromagnetic　absorbing　materials,　magnetic　recording　materials,　photovoltaic　materials　and　low-temperature　joining　materials.　There　exists　intrinsic　size　dependence　in　the　physical　and　mechanical　properties　with　the　microstructure　of　nano-multilayer　films.　Due　to　the　limitation　of　the　preparation　process,　defects　such　as　vacancies　and　dislocations　can　cause　difficulty　in　fully　meeting　the　requirements　of　heat　resistance,　wear　resistance　and　corrosion　resistance　in　the　complex　service　environment,　which　limits　the　further　development　of　nano-multilayer　films.　In　the　field　of　concentrating　circuits　and　chip　fabrication,　nano-multilayer　films　devices　are　often　working　in　a　severe　environment　deviating　from　the　normal　temperature.　However,　metastable　nano-multilayer　films　with　high　surface　free　energy　tend　to　reach　a　state　of　low-energy　and　form　a　stable　structure　by　interdiffusion　of　immiscible　dual　phases,　interlayer　detachment　and　interface　evolution　under　heat.　It　might　result　in　the　extinction　of　melting　point　depression　property,　superhardness　property　and　so　on　due　to　the　destructions　of　the　nano-multilayer　structure.　Therefore,　studying　on　the　microstructure　evolution,　thermal　stability　and　failure　mechanism　of　nano-multilayer　films　is　particularly　important　for　increasing　the　service　life　and　reliability　of　nano-multilayer　systems.　As　a　common　heat　treatment　method,　the　annealing　process　is　widely　used　to　eliminate　defects　in　metals,　so　as　to　achieve　to　modify　the　properties.　For　nano-multilayer　films　operating　at　high　temperatures,　the　annealing　process　is　also　an　effective　means　of　extending　its　service　life.　At　present,　the　main　directions　of　annealing　process　in　nano-multilayer　films　research　and　application　are:　(i)　improving　nano-multilayer　film　performance　by　adopting　different　annealing　temperature,　holding　time　and　cooling　rate;　(ii)　investigating　the　effect　of　annealing　temperature　on　the　thermal　stability　of　nano-multilayer　films　by　increasing　the　annealing　upper　limit　temperature　and　obtain　a　critical　temperature　that　maintains　stability　of　the　interface　of　nano-multilayer.　It　is　found　that　the　appropriate　annealing　process　can　refine　the　nano-multilayer　films　grain　structure,　increase　the　density,　decrease　the　defect　density,　induce　the　formation　of　special　structures,　reinforcing　the　interaction　of　atoms　and　dislocations.　Therefore,　the　light　transmittance　of　the　film　is　increased　with　improvement　of　optical　properties,　as　well　as　the　magnetic,　electrical　and　mechanical　properties　are　significantly　improved;　(iii)　in　addition,　the　nano-multilayer　film　is　annealed　in　a　certain　temperature　range　to　observe　the　bilayer　interface　evolution,　atomic　diffusion　and　new　phase　formation　using　TEM,　XRD　and　other　means.　Thus　the　structural　stability,　chemical　stability　and　mechanical　stability　of　nano-multilayer　film　can　be　studied.　In　this　paper,　the　current　progress　and　challenges　of　annealing　process　in　nano-multilayer　films　modification　and　thermal　stability　research　are　reviewed.　The　influence　of　annealing　parameters　on　the　enhancement　of　nano-multilayer　properties　including　optical　properties,　magnetic　properties,　electrical　properties,　mechanical　properties　is　elaborated.　Furthermore,　it　mainly　focuses　on　the　influencing　mechanism　of　elevated　temperature　annealing　on　the　thermal　stability　and　microstructure　evolution　of　immiscible　nano-multilayer　system.　At　last,　the　further　development　of　annealing　process　for　designing　and　preparing　of　high-strength　and　thermally　stable　nano-multilayer　films　are　prospected,　which　has　important　theoretical　significance　and　application　value　in　materials　welding/joining,　integrated　circuits,　cutting　tools,　absorbing　coatings,　etc.　©　2020,　Materials　Review　Magazine.　All　right　reserved.