Objective To study the COX regression model of 28-day mortality in ARDS patients.Methods Four hundred and fifty-two ARDS patients from 2003 to 2005 was prospectively analyzed in a multi-center and random way. Results In the ARDS pathogeny,sepsis accounted for 41%,severe trauma and operation accounted for 36.3%,severe pancreatitis for 8.8%,and other for 13.9%.The 28-day mortality was 62.2%.Compared with the survived group,the number of dysfunction organs,age,APACHEII,PaCO_2,FiO_2,and A-aDO_2 were higher in the succumbed group,while PaO_2,PaO_2/FiO_2,and pH were lower.Conclusion The 28-day mortality was related with the number of dysfunction organs,age,GLASGOW score,and shock.