The　main　contribution　of　this　paper　is　to　establish　a　new　method　to　evaluate　air　traffic　controller　workloads　in　real　time　and　more　accurately,　which　is　different　from　the　traditional　methods　based　on　aircraft　count　or　complexity　matrixes.　First,　the　relationship　between　air　traffic　control　complexity　(ATCC)　factors　and　the　control　actions　of　controllers　is　depicted　by　a　dynamic　matrix.　Second,　the　task-load,　the　total　time　spent　on　all　the　control　actions　to　control　a　flying　aircraft　that　intends　to　change　its　flight　altitude　because　of　an　ATCC　factor,　is　measured　based　on　the　above-mentioned　relationship.　Last,　the　workload　of　ATCs　is　calculated　by　adding　up　the　task-loads　caused　by　all　factors　of　every　aircraft　in　a　given　time.　In　addition,　an　example　is　given,　and　the　results　show　better　performance　in　comparison　with　the　two　traditional　methods.　©　2012　American　Society　of　Civil　Engineering.