Objective To investigate the clinical effect of low molecular weight heparin calcium (MvH) in the treatment of acute exacerbation of chronic obstructive pulmonary disease(AECOPD)complicated with pulmonary heart disease. Methods 128 AECOPD patients with pulmonary heart disease from January 2016 to December 2016 in our hospital were randomly divided into observation group and control group in equal number by random digit table with EXCEL2007. Apart from the basic treatment like anti infection,oxygen,expectorant,maintenance of water and electrolyte balance and cardiotonic treatment ,the observation group was treated with MvH. The two groups were compared in terms of pre-and post-ventricular end diastolic volume(EDV),end systolic volume(ESV),right ventricular ejection fraction(RVEF),pulmonary artery acceleration time(AT),arterial oxygen pressure(PaO2),arterial partial pressure of carbon dioxide(PaCO2),pH value,whole blood viscosity at low shear the whole blood viscosity at high shear rate,plasma viscosity,hematocrit,plasma D- dimer(D-D). Results After treatment,EDV and ESV of the observation group were significantly lower than the control group (P < 0.05)and RVEF and AT were higher than the control group(P < 0.05). PaCO2 was lower than that of the control group(P < 0.05). PaO2,pH values were higher than those of the control group(P < 0.05). After treatment,the whole blood viscosity,whole blood low shear viscosity at high shear rate,plasma viscosity,hematocrit, plasma level of D-D of the observation group were all lower than those of the control group (P < 0.05). Conclusion Subcutaneous injection with MvH to treat the patients with AECOPD complicated with pulmonary heart disease can improve the blood rheology and improve heart function and blood gas level.