Objective: To investigate the clinical efficacy of low-dose morphine combined with isosorbide dinitrate (Isoket) in the treatment of acute left heart failure (ALHF) on the basis of conventional therapy. Methods: A total of 89 patients with ALHF were selected and divided into treatment group (n=45) and control group (n=44) according to different treatment methods. Both groups received conventional treatments such as cardiotonic, diuretic, antispasmodic and antiasthmatic therapy, and oxygen inhalation. On this basis, the treatment group was treated with low-dose morphine combined with Isoket, while the control group was treated with Isoket alone. Both groups were treated for 24 hours. The clinical efficacy at 30 min, 1 and 24 h after treatment, hemodynamic indexes, blood gas analysis indexes, cardiac function indexes and adverse reactions before and after treatment were compared between the two groups. Results: The total effective rates of the treatment group at 30 min, 1 and 24 h were higher than those of the control group(P<0.05). After 1 and 24 h of treatment, the heart rate(HR), systolic blood pressure(SBP), diastolic blood pressure(DBP) and pulmonary artery wedge pressure(PAWP) of both groups decreased compared with before treatment(P<0.05), and those of the treatment group were lower than those of the control group(P<0.05). The PaO2 and SpO2 increased compared with before treatment, and the PaCO2 decreased, with a better improvement range than the control group (P<0.05). After 24 hours of treatment, left ventricular ejection fraction (LVEF) increased in both groups(P<0.05), and the treatment group was higher than the control group(P<0.05), left ventricular end-diastolic diameter(LVEDD) decreased in all groups (P<0.05), and the treatment group was smaller than the control group (P<0.05). There was no significant difference in the incidence of adverse reactions between the two groups(P>0.05). Conclusion: Low-dose morphine combined with Isoket in treatment of acute left heart failure can quickly improve clinical symptoms, hemodynamics and cardiac function of patients with good safety, which has high clinical promotion value.