High-altitude pulmonary hypertension (HAPH) is a severe and progressive disease caused by chronic hypoxia and subsequent pulmonary vascular remodeling. No cure is currently available owing to an incomplete understanding about vascular remodeling. It is believed that hypoxia-induced diseases can be prevented by treating hypoxia. Thus, this study aimed to determine whether daily short-duration reoxygenation at sea level attenuates pulmonary hypertension under high-altitude hypoxia. To this end, a simulated 5,000-m hypoxia rat model was used to evaluate the effect of short-duration reoxygenation. Results show that intermittent, not continuous, short-duration reoxygenation effectively attenuates hypoxia-induced pulmonary hypertension. The mechanisms underlining the protective effects involved that intermittent, short-duration reoxygenation prevented functional and structural remodeling of pulmonary arteries and proliferation, migration, and phenotypic conversion of pulmonary artery smooth muscle cells under hypoxia. The specific genes or potential molecular pathways responsible for mediating the protective effects were also characterised by RNA sequencing.This study is novel in revealing a new potential method in preventing high-altitude pulmonary hypertension. It gives insights into the selection and optimisation of oxygen supply schemes in high-altitude areas. Overall design: In order to investigate whether intermittent short-duration reoxygenation can prevent HAPH, rats were randomly assigned into four groups and subjected to different oxygenation treatments each day. For the normoxia (N) group, rats were exposed to 400 m (laboratory altitude, gas composition: 21% O2–79% N2) for 24 h each day. For the hypoxia (H) group, rats were exposed to a hypobaric chamber with a pressure of 405 mmHg to simulate hypoxia at about 5000 m for 24 h each day. For the hypoxia + continuous 3-h reoxygenation (C3) group, rats were exposed to a hypobaric chamber similar to group H as well as to 42% O2–58% N2 continuously for 3 h each day. For the hypoxia + intermittent 3-h reoxygenation (I3) group, rats were treated similarly as group H, with 42% O2–58% N2 intermittently for 3 h each day. when the inspired oxygen concentration is 42% at 5000 m, the physiological equivalent altitude is about sea level. After 2-week treatment,whole lung RNA-seq was detected in the N, H, C3, and I3 groups (n=3 for each group).