Objective The aim of this study was to establish a rat models of pulmonary artery hypertention with monocrotaline, and to study the relationship between the evolution of right ventricular function and the evolution of pulmonary artery pressure (PAP) by magnetic resonance (MR) imaging of the right ventricular function. Methods Rat models of pulmonary artery hypertension were established by monocrotaline (MCT). The model rats were divided into 4 groups:the 1-week-PAH group, 2-week-PAH group, 3-week-PAH group, and 4-week-PAH group, and pulmonary artery pressure in the rats was measured by right heart catheterization. After injection of MCT, we used MRI to evaluate the ventricular function of the rats every week. All the measurement data of right ventricular function in the model group were compared with the average pulmonary pressure using Pearson's correlation test.Results There were strong correlations between the parameters of RV function in model group with the average pulmonary pressure (r=-0.823 for RV EF, r=0.732 and 0.803 for RV EDV and RV ESV). At 2 weeks after injection of monocrotaline, the mean pulmonary pressure, right ventricular eject fraction (RVEF), the end-diastolic volume (EDV) and the end-systolic volume (ESV)of right ventricle between rats in PAH and the control group showed no significant difference (P>0.05). But three-four weeks after MCT injection, all these parameters were significantly different in the PAH rats than in control rats (P<0.05).Conclusions As the pulmonary arterial pressure is increased in the rats, the right ventricular function is gradually impaired. For the monitoring of chronic pulmonary artery hypertension in rats, MRI can be used to accurately measure the changes of parameters. The PAH can be indicated by looking at the changes of parameter such as RV EF, RV EDV and RV ESV.