Objective To investigate clinical efficacy of different ventilator parameters on acute left heart failure.Methods One hundred and nineteen patients with acute left heart failure were randomly divided into A,B,C,D group.Patients in A,B,C,D groups were treated separately with higher air pressure,high pressure,medium pressure or low pressure respectively.In each group,clinical efficacy,heart rate (HR),arterial partial pressure of oxygen (PaO2),pulse oxygen saturation (SpO2),partial pressure of carbon dioxide (PaCO2) and pH were measured.Results There were significant differences among the four groups in terms of HR,PaO2,SpO2,PaCO2 and pH (F =32.21,29.46,12.34,36.47,18.38 ; P ＜ 0.05).Compared with that in A,C and D group,the levels of HR,PaO2,SpO2,PaCO2 and pH in B group were significant difference (P ＜ 0.05).Meanwhile those indices in B group were difference among before and after treatment (t =12.25,13.46,8.75,9.83,2.58 ;P ＜ 0.05).The efficacy rates of four groups were significant different (x2 =0.97,P =0.012),and in B group was 93.1％,higher than that of other 3 groups(71.0％,65.6％,51.8％ ;P ＜0.05).Condusion The ventilator parameters(10-15 cmH2O,55％-75％ FiO2 at beginning and later revised the FiO2 to 30％-40％) was proved to be worthy in treating acute left heart failure.