Objective To investigate the clinical efficacy of the treatment of long-term non-invasive positive pressure ventilation (NIPPV) combined with inhaling corticosteroids in patients with stable chronic o0bstructive pulmonary disease(COPD) complicated with respiratory failure,and to investigate the impact of longterm NIPPV combined with inhaling corticosteroids on serum levels of matrix metalloproteinase-9 (MMP-9).Methods Eighty outpatients of stable severe COPD complicated with respiratory failure divided them equally into two treatment groups (the experimental and the control groups).The two groups of patients were given oxygen therapy,inhalation of Salmeterol and fluticasone propionate powder for one year.The experimental group received additionally NIPPV therapy for 1 year.The outcomes measured included St.George's questionnaire (SGRQ) score,MMRC score,6-min working time (6-MWT),arterial partial pressure of oxygen (PaO2),partial pressure of carbon dioxide(PaCO2),Forced expiratory volume in 1 (FEV1％),and the serum levels of MMP-9 before and after treatment,and frequency of acute exacerbations of COPD and hospital says in the last one year and the following 12 months.Results After 1 year,the differences of SGRQ score,MMRC score,6-MWT,PaO2,PaCO2,FEV1％,MMP-9 in the experimental group ((63.38 ±4.46) vs.(52.93 ±4.30),t =10.67,P =0.00;(3.60±0.50) vs.(2.40 ±0.50),t =10.82,P=0.00;(159.90 ±6.50) m vs.(247.10±9.66) m,t=47.39,P=0.00;(56.85 ± 1.67) mm Hg vs.(66.10 ±2.59) mm Hg,t =10.67,P =0.00;(60.38 ±3.58)mm Hgvs.(51.88 ±3.05)mm Hg,t=10.82,P=0.00; (38.93 ±3.22)％ vs.(42.12 ±3.11)％,t=47.39,P =0.00;(182.58 ±6.60) μg/L vs.(171.73 ±6.19) μg/L,t =7.58,P =0.00) were statistically significant compared to the control group ((63.88 ± 4.88) vs.(54.30 ± 4.13),t =8.77,P =0.00; (3.65 ± 0.48) vs.(2.70±0.46),t =8.97,P =0.00;(157.98 ±5.97) m vs.(218.08±13.12) m,t =26.38,P=0.00;(56.65 ±1.51)mm Hg vs.(62.60 ± 1.91)mm Hg,t=8.77,P=0.00; (60.20 ±3.52)mm Hg vs.(56.25 ±3.09)mm Hg,t =8.97,P =0.00; (38.93 ±2.96) ％ vs.(40.70 ±3.27)％,t =26.38,P =0.00; (180.55 ±4.78) μg/L vs.(173.05 ± 5.28) μg/L,t =6.66,P =0.00).The frequency of acute exacerbations of COPD and hospital stay days were significantly decreased in the experimental group than in the control group.Conclusion Long-term NIPPV combined with inhaling corticosteroids could significantly improve the quality of life and lower the serum levels of MMP-9 of patients with severe stable COPD complicated with respiratory failure.