This is an open, one-arm, prospective clinical collaborative study. This study is aimed to observe the efficacy and safety of the new combined therapy of Ruxolitinib and Etoposide combined with DDGP regimen ( cis-Platinum, Dexamethasone, Gemcitabine and Pegaspargase) in the first-line induction therapy patients with primary central nervous system lymphoma. A total of 30 patients plan to participate in the study. The primary endpoint is objective remission rate (ORR) of hemophagocytic syndrome, and the secondary endpoints include progression-free survival (PFS) , objective remission rate (ORR) of lymphoma, overall survival (OS), and adverse events(ADR).