Objective To modify the model of right ventricular outflow tract obstruction (RVOTO) in rats, and to search for the optimal method for the model establishment. Methods Thirty male SD rats were randomly divided to three groups: RVOTO group, sham group and control group. There were 10 rats in each group. The animals in RVOTO group were given pulmonary arterial constriction (PAC), those in sham group thoracotomy without PAC, and those in control group no surgical operation. The heart specimens were harvested after 4 weeks. The thickness of right ventricle, the hyperplastic state of myocardiac cells and the fiber volume ratio of myocardiac cells were analyzed by the t test. Results The modified RVOTO model was established in 4 weeks. The thickness of right ventricle in RVOTO group was greater than that in sham group and control group [RVOTO group: (0.938±0.054) mm; sham group: (0.260±0.436) mm; control group: (0.249±0.587) mm, P=0.000]. The thickness of right ventricular outflow tract was significantly increased as compared with the free wall of right ventricle. The fiber volume ratio of myocardiac cells in RVOTO group was significantly higher than in sham group and control group [RVOTO group: (20.17±5.87)%; sham group: (8.35±4.23)%; control group: (7.57±2.31)%, P=0.000]. Conclusion The modified model of RVOTO in rats is significantly cheaper, easier, safer and more consistent with the clinical features than the traditional one. Key words: Right ventricular outflow tract obstruction; Right ventricular hypertrophys; U-shaped clamp; Models, animal