Endothelial dysfunction is essential in pulmonary arterial hypertension (PAH) pathogenesis and is considered to be a therapeutic target of PAH. Curcumol is a bioactive sesquiterpenoid with pharmacological properties including restoring endothelial cells damage. This study aimed to evaluate the effect of curcumol on PAH rats and investigate its possible mechanisms. PAH was induced by subcutaneous injection of 60 mg/kg monocrotaline (MCT) in male Sprague Dawley rats. Curcumol (12.5, 25, and 50 mg/kg/day) were administered by intragastric administration for 3 weeks. The results demonstrated that curcumol dose-dependently alleviated MCT-induced right ventricular hypertrophy and pulmonary arterial wall thickness. In addition, endothelial-to-mesenchymal transition (EndMT) in the pulmonary arteries of MCT-challenged rats was inhibited after curcumol treatment, as evidenced by the restored expressions of endothelial and myofibroblast markers. The possible pharmacological mechanisms of curcumol were analyzed using network pharmacology. After screening the common therapeutic targets of PAH and curcumol by searching related databases and comparison, pathway enrichment was performed and AKT/GSK3β was screened out as a possible signaling pathway which was relevant to the therapeutic mechanism of curcumol on PAH. Western blot analysis verified this in lung tissues. Moreover, combination of TNF-α, TGF-β1 and IL-1β-induced EndMT in primary rat pulmonary arterial endothelial cells were blocked by curcumol, and this effect was resembled by PI3K/AKT inhibitor LY294002. Above all, our study suggested that curcumol inhibited EndMT via inhibiting the AKT/GSK3β signaling pathway, which may contribute to its alleviated effect on PAH. Curcumol may be developed as a therapeutic for PAH in the future.