Abstract：Objective To investigate the effect of noninvasive mechanical ventilation in elderly patients with pulmonary hypertension and respiratory failure.  Methods    A total of 68 patients with pulmonary arterial hypertension induced respiratory failure admitted to our department from October 2019 to November 2020 were selected as the research objects and divided into control group and observation group by the principle of parity method, with 34 cases in each group. Invasive mechanical ventilation was used in the control group and non-invasive mechanical ventilation was used in the observation group. The therapeutic effects, blood gas analysis, oxygenation index, inflammatory factors and incidence of complications were compared between the two groups. Results After treatment, the effective rate of the observation group was higher than that of the control group, the complication rate was lower than that of the control group, the difference between the two groups was statistically significant （χ2＝ 6.275, 5.314, all P＜0.05）. PaCO2, endothelin-1, interleukin-6 and C-reactive protein were all lower than control group, while PaO2, SaO2, oxygenation index and BNP were all higher than those of the control group. The differences between the two groups were statistically significant （t＝5.902, 4.484, 10.555, 6.436, 2.534, 3.662, 8.513, 30.181, all P＜0.05）. Conclusion Non-invasive mechanical ventilation is ideal for the diagnosis and treatment of elderly pulmonary arterial hypertension and respiratory failure. It can improve the oxygenation function, weaken the expression of inflammatory factors, correct the blood gas index, and increase the level of brain natriuretic peptide. It has fewer complications, is safe and effective, and is worthy of promotion.