Background: The impact of pre-existing interstitial lung disease (ILD) on the severity and mortality of COVID-19 remains largely unknown. The purpose of this meta-analysis was to investigate the prevalence of ILD among patients with COVID-19 and figure out the relationship between ILD and the poor clinical outcomes of COVID-19. Methods: A systematic literature search was conducted in the PubMed, EMBASE, Web of Science and MedRxiv Database from 1 January 2020 to 26 May 2021. Results: 15 studies with 135,263 COVID-19 patients were included for analysis of ILD prevalence. The pooled prevalence of comorbid ILD in patients with COVID-19 was 1.4% (95% CI, 1.1%-1.8%, I2 = 91%) with significant between-study heterogeneity. Moreover, the prevalence of ILD in non-survival patients with COVID-19 was 2.728-folds higher than that in corresponding survival patients (RR = 2.728, 95% CI 1.162-6.408, I2 = 54%, p = 0.021). Additionally, 2-3 studies were included for comparison analysis of clinical outcome between COVID-19 patients with and without ILD. The results showed that the mortality of COVID-19 patients with ILD was remarkably elevated compared with patients without ILD (RR = 2.454, 95% CI 1.111-5.421, I2 = 87%, p = 0.026). Meanwhile, the pooled RR of ICU admission for ILD vs. non-ILD cases with COVID-19 was 3.064 (95% CI 1.889-4.972, I2 = 0, p < 0.0001). No significant difference in utilizing rate of mechanical ventilation was observed between COVID-19 patients with and without ILD. Conclusions: There is great variability in ILD prevalence among patients with COVID-19 across the globe. Preexisting ILD is associated with higher severity and mortality of COVID-19.