Abstract： Objective To explore the function of 120 command information systems for emergency medical rescue in the 5· 12 Wenchuan Earthquake. Method To analyze various functions of Chengdu 120 command center information systems during the disaster resulted from the catastrophic earthquakes. Results As soon as 38 minutes after the Wenchuan earthquake with the magnitude of 8 (measured 8 on the Richter scale) happened at 14:28:04,calls flooded the Chengdu 120 center for help as many as 3-4 times the usual in a brief period. Immediately , the center opened 8 spare Alarm Reception stations, launching all sorts of function of both wire and wireless digital trucking systems,keeping track of database information, taking LED, road monitoring system, GIS, GPS for visual tracking and displaying vehicles and the messages about casualties. They received 6479 SOS calls and 14 749 calls within 58 hours.The first 58 hours after the earthquake happened, 120 center had dispatched ambulances 1184 time and sents 705 medical teams of more than 3000 medical staff for relief to hardest quake-hit region , which more than 6000 casualties were rescued and transported. The following 20 days, assigned 244 hospitals, 2526 rescuer vehicles at 5 airports, railway stations and Zipinpu Reservoir to pick up the injuries of 1518 persons and transfer 2151 persons to other province for medical treatment. Conclusions The 120 communication modalities and command development should be diversified and the command information systems construction should meet both peacetime and wartime needs with gradual, scienlifical, reasonable and flexible improvements. Provided that those improvements are well done,we shall ensure 120-lifeline going smoothly just in case the disasters occurs.