Because　traffic　delays　and　queues　have　a　serious　impact　on　intersections　and　even　entire　roadway　networks,　this　paper　attempts　to　study　the　optimization　algorithm　of　signal　timing　for　individual　intersections.　The　non-linear　optimization　model　which　is　applicable　for　an　individual　intersection　can　be　built　up　by　using　an　ant　colony　algorithm　based　on　mesh　strategy.　The　programs　are　made　by　MATLAB　in　which　some　relevant　parameters　and　algorithm　rules　are　ameliorated.　Taking　some　typical　intersections　in　Beijing　as　an　example,　the　non-linear　model　is　established　through　programming　in　MATLAB.　The　optimization　model　is　verified　by　estimating　some　targets　after　conducting　a　contrast　study　between　the　ones　made　by　the　Webster　Method　and　the　current　timing　condition　derived　from　an　ant　colony　algorithm.　The　results　suggest　that　the　ant　colony　algorithm　based　on　mesh　strategy　is　suitable　for　solving　the　problem　of　signal　timing　during　peak　periods.　This　new　optimization　algorithm　can　improve　the　condition　at　signalized　intersections　and　provide　a　new　effective　method　for　solving　the　problem　of　signal　timing　at　intersections.　©　2009　ASCE.