Purpose: This retrospective study aimed to evaluate the prognostic value of metabolic parameters in baseline fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for pediatric lymphoblastic lymphoma (LBL). Method: Thirty patients with LBL who underwent baseline 18F-FDG PET/CT from April 2013 to November 2018 were enrolled. Their metabolic parameters including maximum standardized uptake value (SUVmax), total metabolic tumor volume (TMTV), and total lesion glycolysis (TLG) were measured and compared with those from different clinical characteristic groups. Event-free survival (EFS) and overall survival (OS) curves were constructed using the Kaplan–Meier method and compared with the log-rank test. Results: The patients with stage Ⅳ had higher TMTV than stage Ⅲ (mean 580.66cm³ vs. 176.52cm³; p=0.031). No statistical significance in SUVmax and TLG was observed between patients with stages Ⅲ and Ⅳ (p=0.061; p=0.291). After a median follow-up of 41.5 months (range of 1–86 months), the patients with a low TMTV (<242.91cm³) had better 3-year EFS rate compared with those with a high TMTV (88.9% vs. 56.3%; p=0.036). However, SUVmax and TLG were not predictive of EFS(p=0.874; p=0.152). Conclusions: TMTV may be a potential PET/CT metabolic parameter for predicting the prognosis of pediatric lymphoblastic lymphoma. A high TMTV indicates a poor outcome. However, SUVmax and TLG are not related to the prognosis of pediatric lymphoblastic lymphoma.