Objective To analyze the correlation between inflammatory index and respiratory failure (RF) in patients with idiopathic pulmonary fibrosis (IPF). Methods The clinical data of 169 patients with IPF admitted in the First Hospital of Lanzhou University from January 2019 to October 2021 were collected, and then divided into the group with respiratory failure (RF group, n=84) and the group without respiratory failure (non-RF group, n=85) according to the arterial blood gas analysis. The clinical data such as blood routine and biochemical data were collected for comparison between the two groups. Logistic regression analysis was performed to screen the possible risk factors of RF in IPF patients; Spearman correlation analysis was used to explore the correlation between multiple inflammatory indicators and between PaO₂ level and inflammatory indicators; The diagnostic value of inflammatory indicators was analyzed in IPF patients complicated with RF by using the ROC curve. Results NLR (neutrophil to lymphocyte ratio) and PLR (platelet to lymphocyte ratio) were significantly higher in RF group than in non-RF group, while LMR(lymphocyte to monocyte ratio) were significantly lower than those in non-RF group, the differences were statistically significant (P<0.05). Spearman correlation analysis was conducted on NLR, PLR, LMR and CRP, PCT and PaO₂ levels in all patients, it was indicated that NLR, PLR were positively correlated with CRP and PCT (P<0.05), while LMR was negatively correlated with CRP and PCT (P<0.05), moreover, there was a negative correlation between NLR and PaO₂ level (P<0.05), and a positive correlation between LMR and PaO₂ level (P<0.05). Logistic multifactor regression analysis suggested that smoking and increased NLR were independent risk factors for RF in IPF patients. ROC analysis indicated that NLR and LMR could be effectively used in diagnosis of IPF complicated with RF, and the area under the curve was 0.738(95%CI 0.663-0.812) and 0.736(95%CI 0.660-0.812), respectively.PLR had limited diagnostic value for IPF complicated with RF, and the area under the curve was only 0.629(95%CI 0.545-0.714), while the combined diagnostic ability of NLR, PLR and LMR was higher than the three single indexes, and the area under the curve was 0.760(95%CI 0.689-0.832). Conclusions Elevated NLR is an independent risk factor for RF in IPF patients. NLR, PLR, LMR and their combination have certain diagnostic value for IPF patients complicated with RF, and the combined diagnostic ability of the three is better than the three single indicators alone.