Abstract: Objective To investigate the effect of phosphatidylinositol 3-kinase（PI3K）-protein kinase B（Akt）-metal-regulatory transcription factor 1（MTF-1） signaling pathway on pulmonary artery smooth muscle cells（PASMC） proliferation and migration in hypoxia-induced pulmonary hypertension（PH） rats. Methods In animal experiments, 16 adult male Sprague-Dawley（SD） rats were randomly divided into two groups: control group（Ctrl group） and hypoxia-induced PH group（hypoxia-PH group）. In hypoxia-PH group, rats were placed in a glass chamber oxygen concentration（10.0±0.2）%, and chronic PH model was established by normoxia for 2 weeks after continuous hypoxia for 3 weeks. Rats in Ctrl group were normally fed in specific pathogen free（SPF） room. At the end of the 5^th week after modeling, mean pulmonary arterial pressure（mPAP） was measured by right heart catheterization and morphological changes of pulmonary artery were assessed by HE staining. Histoimmunofluorescence was used to observe changes of MTF-1 and placental growth factor（PlGF）. Western-blot was used to detect the expressions of phospho-Akt（p-Akt）, total-Akt（T-Akt）, MTF-1 and PlGF in lung tissues. In cell experiments, PASMC were derived from 5 untreated rats, and PASMC from each rat were divided into three groups: control-PASMC（Ctrl）, hypoxia-PASMC（hypoxia） and hypoxia+LY294002-PASMC（hypoxia+LY294002） group. Cells were treated with 100 μmol/L cobalt chloride for 24 h to mimic hypoxia conditions in hypoxia group and hypoxia +LY294002 group. PI3K-Akt pathway inhibitor LY294002 was administrated 30 min before cobalt chloride intervention in hypoxia +LY294002 group. Cells were untreated in Ctrl group. Western-blot was used to detect the expressions of p-Akt, T-Akt, MTF-1 and PlGF in PASMC. PASMC proliferation and migration were evaluated by 5-ethynyl-2’-deoxyuridine（EdU）, flow cytometry and scratch assay. Results In animal experiments, hypoxia-PH rats showed elevated mPAP, thickened pulmonary vascular wall, and right ventricular hypertrophy（all P＜0.05）. Histoimmunofluorescence and Western-blot showed that p-Akt, MTF-1 and PlGF expression in hypoxia-PH rats were significantly higher than those in Ctrl rats（P＜0.05）. In cell experiments, Western-blot demonstrated that the expressions of p-Akt, MTF-1 and PlGF in hypoxia group were significantly higher than those in Ctrl group（P＜0.05）, which was reversed by LY294002, while no significant difference of T-Akt was shown（P＞0.05）. Meanwhile, EdU, flow cytometry and scratch assay demonstrated that proliferation and migration levels obviously elevated in hypoxia group, which could be inhibited by LY294002 the ratio of positive cells in EdU assay: Ctrl（0.33±0.06）% vs hypoxia（0.86±0.06）% vs hypoxia+LY294002（0.41±0.14）%, F=24.13, P＜0.01; the ratio of G2+M cells in flow cytometry: Ctrl（4.49±0.39）% vs hypoxia（16.86±1.74）% vs hypoxia+LY294002（4.99±0.48）%, F=195.70, P＜0.01; migration rate of cells in scratch assay at 24 h: Ctrl（21.80±3.88）% vs hypoxia（41.53±1.96）% vs hypoxia+LY294002（25.94±6.63）%, F=15.47, P＜0.01; at 48 h: Ctrl（39.92±1.06）% vs hypoxia（73.01±3.96）% vs hypoxia+LY294002（42.97±4.80）%, F=75.61, P＜0.01. Conclusion Hypoxia activates the PI3K-Akt signaling pathway, further promotes MTF-1 and PlGF expression, and ultimately leads to PASMC proliferation and migration.