Objective To investigate the safe range of vital signs of pregnant women pulmonary hypertension (PH). Study design Retrospective study. Setting The largest First-class Hospital at grade 3 in Northwestern China Population pregnant women with PH in Intensive care unit (ICU). Methods This of consecutive obstetric patients with PH admitted to ICU of the First Affiliated Hospital of Air Force Military Medical University of China, from January 2011 to May 2020, consisted of 92 cases analyzed using time-dependent Cox regression to consider the dynamic features of vital signs. Main outcome measures Maternal mortality Results 7/92 maternal deaths occurred. Three vital signs were identified as risk factors in the maternal in-hospital mortality model via backward selection: SpO2（HR，0.93；95%CI，0.88-0.97；P=0.003）, heart rate（HR，0.94；95%CI，0.90-0.99；P=0.027）, and mean arterial pressure (MAP) （HR，1.09；95%CI，1.00-1.18；P=0.045）. The optimal range of SpO2 <73%, MAP was 65–95 mmHg, and heart rate was 59–125 beats per minute (bpm). Further exploration showed that the cumulative and the longest consecutive time of abnormal vital signs also affect the outcome. For example, SpO2<73% accumulated for 5 h or continuously up to 2 h increases mortality. Conclusions: Maintaining SpO2>73%, MAP at 65–95mmHg, and heart rate at 59–125 bpm can significantly reduce in-hospital maternal mortality. The effects of the abnormal SpO2, heart rate, and MAP on in-hospital maternal mortality should be combined with the cumulative time and the longest duration. Funding Dr. Binxiao Su is supported by the National Institutes of Health (NIH) grant 81870961