Background Pre-exiting chronic lung disease was a poor prognostic factor for pneumocystis jiroveci pneumonia (PJP). However, the clinical characteristics and the prognostic factors of HIV negative PJP patients (non-HIV-PJP) with interstitial lung disease (ILD) remains unclear. Methods This was a retrospective study of hospitalized patients with confirmed PJP and ILD at Peking Union Medical College Hospital between January 2014 and December 2020. The enrolled patients were stratified based on

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... presence or absence of ILD and the presence of fibrotic ILD (FILD) or nonfibrotic ILD (non-FILD). The log-rank test and Cox regression models were used to analyze the prognostic factors for PJP patients with different pre-existing statuses. Results Among 836 hospitalized individuals with PJP, there were 378 non-HIV-PJP with complete clinical-radiological-follow-up data. Among them, there were 133cases (35.2%) with non-HIV-ILD-PJP, and 70 patients were classified as fibrotic ILD-PJP. The all-cause mortality rate for ILD-PJP group was higher than that of non-ILD-PJP group (57.9% vs 38.4%, Log-rank = 12.2, p < 0.001, However, the all-cause mortality was similar between FILD-PJP and non-FILD-PJP (Log-rank = 0.03, p > 0.05). Co-infection with aspergillosis(HR = 2.89, χ2 = 5.0, p = 0.02, 95%CI:1.14–7.28), honeycomb in the chest HRCT(HR = 16.3, χ2 = 16.8, p < 0.001, 95%CI:4.3–62), invasive ventilation(HR = 3.02, χ2 = 7.1, p < 0.01, 95%CI:1.34–6.82) and non- invasive ventilation(HR = 6.2, χ2 = 16.7, p < 0.001, 95%CI:2.58–14.9 ) were independent survival risk factors for non-HIV-ILD-PJP. Non-invasive ventilation support (HR = 928.56, χ2 = 7.3, p < 0.01, 95%CI:6.6-130796.5) and the serum D-dimer (HR = 1.2, χ2 = 10.9, p < 0.001, 95%CI:1.01–1.34) were independent survival risk factors for fibrotic ILD-PJP patients. Conclusions Pre-exiting ILD is independently associated with poor survival of PJP patients. Co-infection with aspergillosis, honeycomb in the chest HRCT, invasive ventilation and non- invasive ventilation were independent survival risk factors for ILD patients complicated with PJP.