Search　and　recognition　is　the　most　important　part　of　the　covert　channel　analysis.　At　present,　most　of　the　covert　channel　search　methods　are　static　analysis　on　system.　It　has　many　shortcomings,　such　as　heavy　workload,　omission,　inaccurate,　and　so　on.　It　is　necessary　to　find　the　dynamic　search　method　for　covert　channel　during　a　system　is　running.　This　paper　presented　a　covert　channel　dynamic　search　method　based　on　grey　relational　analysis　algorithm　(GRAA)　in　gray　theory.　The　method　is　efficient　and　can　be　used　in　conjunction　with　existing　covert　channel　search　methods.　Finally,　a　closed-loop　feedback　will　be　formed　so　that　the　system＇s　safety　mechanism　can　be　self-improvement　gradually.　©　2012　The　Journal　of　China　Universities　of　Posts　and　Telecommunications.