Abstract： AIM To evaluate the cardiovascular function of pilots with frequent premature contractions(PCs)who have undergone treatment in a hypobaric hypoxic environment,in order to provide sufficient theoretical basis for their flight safety decisions after treatment.METHODS Simulate hypobaric hypoxic environment at an altitude of 5000-meter using a low-pressure chamber,and monitor arrhythmia,blood pressure fluctuations,simulated flight maneuverability,and heart rate variability of pilots in hypobaric hypoxic environment using equipment such as dynamic electrocardiogram,dynamic blood pressure,psychomotor ability testing,and heart rate variability analysis.RESULTS The simulated flight ability of 6 patients was not significantly affected by to hypobaric hypoxic environment;There was no significant increase in the frequency and proportion of premature atrial and ventricular contractions;The changes in systolic blood pressure,diastolic blood pressure,pulse pressure difference,and mean arterial pressure were not significant compared to normal conditions;The analysis of heart rate variability showed that compared to normal conditions,the patient's extremely low frequency(VLF)significantly increased(P<0.05),and the autonomic nervous system balance ability(ANS balance)significantly decreased(P<0.05),with no significant difference in other indicators;In a hypobaric hypoxic environment of 5000-meter,the patient's blood oxygen saturation significantly decreased,but it was still within the normal tolerance range,and no discomfort symptoms such as dizziness appeared in the subjects.CONCLUSION Evaluating the cardiovascular function of pilots after frequent PCs are cured in a hypobaric hypoxic environment can provide a reference basis for precise aviation medical evaluation and flight safety assessment.