This study aimed to analyze the clinical characteristics and prognostic factors of patients, divided into over 40-year-old group or not, with precursor T-cell lymphoblastic lymphoma (Pre-T-LBL). Based on the retrospective analysis of the clinical data of 59 patients with Pre-T-LBL during the period from December 2010 to December 2015, albumin level, anemia, pleural or pericardial effusion, protocol, therapy response, mediastinal mass, lactate dehydrogenase (LDH), and international prognostic index (IPI) or age-adjusted international prognostic index (aaIPI) were summarized. For patients aged <40 years, factors correlating with poor progression-free survival (PFS) were pleural or pericardial effusion, regimen, albumin level and therapy response. Pleural or pericardial effusion, aaIPI score, regimen, LDH increased, albumin level, therapy response and mediastinal mass were all related with poor overall survival (OS). In the patients aged ≥40 years, only anemia associated with PFS. However, anemia, involvement of bone marrow and therapeutic response were all related with poor OS. In conclusion, the patients with Pre-T-LBL are characterized by a low incidence and bad prognosis. Different prognostic factors can be discovered for patients over 40-year-old with Pre-T-LBL comparing to the youngers. New prognostic evaluation factors should be explored for patients ≥40 years old.