Objective：To explore the prognostic implication of the platelet - lymphocyte ratio(PLR)in primary central nervous system lymphoma(PCNSL)and to find a modified IELSG scoring system suitable for the Asian PCNSL population. Methods：The clinical data of 72 patients with PCNSL from the First Affiliated Hospital of Nanjing Medical University between June 2011 and December 2021 were retrospectively analyzed. Kaplan - Meier method，univariate and multivariate Cox regression analyses were performed for survival analysis and prognostic factors evaluation. Results：Median progression-free survival(PFS)and overall survival (OS)were 17 months and 39 months in PCNSL patients，respectively. Univariate Cox regression analysis confirmed PLR ≥107(P=0.022， P=0.038)，age 54≥ years(P=0.043，P=0.027)，LDH/ULN＞2(P=0.080，P=0.064)，CSF protein/ULN＞2(P=0.051，P=0.023)， ECOG≥2(P=0.029，P=0.027)and modified IELSG high - risk group(P=0.064，P=0.001)were associated with shorter PFS and OS. Multivariate Cox regression analysis confirmed PLR ≥107(P=0.011，P=0.022)and ECOG≥2(P=0.013，P=0.015)were independent risk factors for PFS and OS of PCNSL patients. Conclusion：PLR may be used as an indicator to evaluate the prognosis of PCNSL.