Objective To study the detection accuracy of MRI and ultrasound on left ventricular function in patients with hypertension complicated with ventricular hypertrophy and evaluate the clinical citation value of the two methods. Methods A total of 92 cases of patients with hypertension were divided into hypertension group and LVH group according to left ventricular mass index (LVMI). At the same time, another 50 healthy examiners in our hospital were selected as control group, and the three groups were given B-ultrasound and CMR examination. The cardiac function indicators measured by the two examination methods were compared, and the consistency was analyzed by Bland-Altman diagram. Results B-ultrasound and MRI showed that the LVMI in control group, hypertension group and LVH group showed an upward trend (P<0.05), and the B-ultrasound measurement results of each group were lower than CMR (P<0.05). The PER and TPER in hypertension group measured by B-ultrasound and MRI were higher than those in control group, and the LVEDV, LVESV, SV, PER and TPER in LVH group were higher than those in control group and hypertension group (P<0.05), and the LVEDV, SV and PER measured by B-ultrasound were lower than CMR while the TPER was higher than CMR (P<0.05). Bland-Altman diagram analysis showed that the mean value difference of B-ultrasound and CMR was large in the measurement of left ventricular cardiac function indexes, and the measurement results of B-ultrasound were low on LVEDV, LVESV, SV, EF and PER while the measurement result of TPER were high, but the two methods had good consistency in LVEDV, LVESV, PER and TPER. Conclusion The accuracy of B-ultrasound in cardiac function indexes of patients with hypertension and LVH is lower than that of MRI. The measurement results of the two methods are quite different, but the consistency is good.