Objective To explore the applications of color Doppler echocardiography in left ventricular hypertrophy due to hypertension with left heart failure. Methods A total of 60 cases left ventricular hypertrophy due to hypertension with left heart failure patients in People Hospital of Xinyu City in Jiangxi Province from February 2016 to February 2019 were selected as the observation group, according to different grades of cardiac function, 26 cases were classified as grade Ⅱ, 30 cases as grade Ⅲand 4 cases as grade Ⅳ. Another 50 healthy individuals in the same period were selected as the control group. The left atrial diameter (LAD), left ventricular posterior wall thickness (LVPWT), left ventricular end diastolic diameter (LVEDD), left ventricular ejection fraction (LVEF), E value, A value and E/A value of the two group of study object, different cardiac function patients were observed. Results The LAD, LVPWT, LVEDD, A value of the observation group were higher than those of the control group, the LVEF, E value, E/A value of the observation group were lower than those of the control group, the differences were statistical significance (P＜0.05). The LAD、LVPWT、LVEDD、A value of cardiac function grade Ⅱpatients were lower than those of grade Ⅲ, grade Ⅳpatients, the LVEF, E, E/A value of cardiac function grade Ⅱpatients were higher than those of grade Ⅲ, grade Ⅳpatients, the differences were statistical significance (P ＜0.05). There was no significant difference in LAD, LVPWT,LVEDD, LVEF, E value, A value and E/A value between grade Ⅲpatients and grade Ⅳpatients (P＞0.05). Conclusion The color doppler echocardiography detection could effective evaluate cardiac function of patients on left ventricular hypertrophy due to hypertension with left heart failure, which can determine cardiac function classification, and provide theoretical basis for guiding clinical treatment.