Intelligent　traffic　control　system　is　an　important　part　of　Intelligent　Transportation　System.　Now,　there　are　several　traffic　control　systems　in　a　city.　Because　the　different　systems　use　their　own　exclusive　protocols,　there　has　the　problem　of　different　types　of　products　incompatibility.　So　to　help　information　exchange　among　different　systems　and　products,　it　is　necessary　to　do　research　to　the　communications　standard　of　traffic　control　system.　Traffic　signal　control　markup　language　SignalML　(Signal　Markup　Language)　based　on　XML　is　a　kind　of　data　standard　which　is　used　to　describe,　pack,　store　and　transfer　signal　control　data　for　different　signal　controllers　to　facilitate　to　transfer　and　share　the　signal　control　data　and　control　information.　It　describes　the　data　format　in　traffic　control　system　such　as　intersection　geometry　structure,　signal　control　type　and　signal　control　parameter,　traffic　flow　data　etc.　The　paper　gives　out　the　definition　of　SignalML　language,　introduces　the　layer　structure　and　builds　a　test　platform　to　testify　the　validation　of　the　communications　standard　in　traffic　control　system.　The　result　shows　it　is　useful　to　communications　of　traffic　control　system.　©2006　IEEE.