Fuzzy　logic　presented　in　the　paper　simulates　the　control　logic　of　signal　controller　at　oversaturated　intersection　during　peak　time.　Fuzzy　logic　rules　of　green　time　extension　value　are　given　based　on　the　vehicle　queue　length.　The　available　green　time　of　each　approach　is　decided　according　to　statistical　average　queue　length　and　the　fuzzy　logic　rules.　The　fuzzy　logic　control　optimization　effect　was　compared　with　the　effect　of　traditional　optimization　method　by　SimTraffic　simulation.　The　peak　hour　traffic　flow　field　data　of　Ping　Le　Yuan　intersection　in　Beijing　city　is　observed.　Based　on　the　delay　statistics,　the　optimization　method　using　fuzzy　logic　produced　preferable　improvement　over　traditional　timing　method.　This　method　has　the　popularizing　market.