Objective To investigate the expression of circulating microRNA (miRNA) of rats with hypobaric hypoxia‐induced pulmonary hypertension (HPH) .Methods Commercial rat miRNA microarray was employed to detect and analyze the circulating miRNA profile in the serum samples of Sprague‐Dawley rats with hypobaric hypoxia‐induced HPH and controls .Furthermore ,differentially expressed candidate circulating miRNAs between HPH and control groups were validated by Real‐time quantitative PCR based on the case‐control study ,and receiver operating characteristic curve (ROC ) analysis was used to test the performance of four differentially expressed circulating miRNAs in discriminating HPH and control groups .Results Compared with those in the control group ,13 upregulated miRNAs and 10 downregulated miRNAs were identified in hypobaric hypoxia‐induced HPH rats by using miRNA microarray . And differentially expressed miR‐451 , miR‐505 , let‐7d and miR‐214 were validated by using RT‐PCR .ROC analysis showed that the area under the curve of miR‐451 ,miR‐505 and let‐7d was 0 .979 ,0 .938 and 0 .993 in discriminating HPH and control groups ,respectively .Conclusion The aberrant expression of circulating miR‐451 ,miR‐505 and let‐7d in serum may be correlated with the pathogenesis of HPH .