Objective To evaluate the cardiac function in rats with hyperthyroid heart disease by velocity vector imaging (VVI). Methods Rat models of hyperthyroid heart disease were established. The levels of serum TT3, TT4 and electron microscopy in the minor changes of rats of hyperthyroid heart disease were detected by ultrasound VVI. Results The systolic and diastolic radial velocity (Vs, Vd), radial strain (Sr), systolic and diastolic radial strain rate (SRr) of model group were lower than control group (P < 0.05). Serum TT3 and TT4 levels of model group were increased (P < 0.05) compared with the control group. There was no significant change for myocardial structure and no obvious hypertrophic myocardial fiber structure in the control group. The degree of myocardial interstitial fibrosis in the model group was significantly higher than that in the control group. Conclusion VVI plays an important role in evaluating the cardiac function of hyperthyroid heart disease.