Objective:To investigate the efficacy of plasma exchange (PE) in treatment of patients with acute respiratory distress syndrome (ARDS).Methods:Forty-two patients who met the inclusion criteria in the intensive care unit of Chenzhou First People′s Hospital were randomly divided into control group and plasma exchange (PE) group with 21 cases in each group. The control group received conventional treatment; while the PE group received conventional treatment plus PE. The mechanical ventilation time (MVT), length of ICU stay (ICU LOS), 28-day mortality and 90-day mortality of patients were analyzed. The oxygenation index, SOFA score, norepinephrine (NE) dose, C-reactive protein (CRP), procalcitonin (PCT) and IL-6 levels were evaluated before and after treatment.Results:In the control group the oxygenation index, IL-6, PCT and CRP were significantly improved after treatment ( t=-4.50, 2.46, Z=-3.53, t=5.55, all P<0.05), but the SOFA score and NE dose were not significantly changed ( t=1.98, Z=-0.47,all P>0.05). In the PE group, the oxygenation index, SOFA score, IL-6, PCT, CRP were significantly improved and the NE dose was reduced after treatment ( t=2.18, 9.23, 5.26, Z=-3.77, t=7.27 and Z=-2.54,all P<0.05). The oxygenation index, SOFA score, IL-6, CRP were significantly better after treatment and NE dose was lower in PE group than those in the control group ( t=2.18, -2.21, -2.12, -2.61 and Z=-2.11, all P<0.05). Compared with the control group, the MVT(14.0±5.2d vs. 18.4±6.3d), ICU LOS(19.3±4.9d vs. 23.2±7.3d) and 28-day mortality (14.3%(3/21) vs. 42.8%(10/21)) in the PE group were significantly decreased ( t=-2.48, -2.04 and χ2=4.20,all P<0.05). There was no significant difference in the 90-d mortality between the two groups (28.6%(6/21) vs. 52.4%(11/21), χ2=2.47, P=0.208). Conclusion:Therapeutic plasma exchange can significantly reduce the inflammatory response, improve the organ function and reduce the short-term mortality of ARDS patients.