Objective To investigate the differences in the epidemiological characteristics of patients in pre-hospital medical care before and after “5 · 12” Wenchuan earthhquake in Deyang city.Methods Comparison was made between the epidemiological features of cases treated in Deyang emergency medical center from the January 1,2007 through the December 31,2007 before the earthquake (the pre-earthquake group) and those treated from the January 1,2009 through the December 31,2009 after the earthquake ( the post-earthquake group) with the criteria of international classification of diseases (ICD-10).Results ( 1 ) There were 11 325 patients medically cared before earthquake and 16 265 patients after disaster.The distribution of sex,age,the top five causes,the seasonal and diurnal variations of emergency call,radius of service circle of pre-hospital medical care cases were no significantly different between the two groups ( P ＞ 0.05 ).( 2 ) The time required for scheduling ambulance and time consumed for the transportation of patients in the post-earthquake group were less than those in the pre-earthquake group ( P ＜ 0.05 ).Conclusions The efficiency of medical care done by 120 Emergency Command Center in Deyang city has been improved significantly in ease of without change in epidemiological features of patients after reconstruction of disaster area.