Abstract: Objective To analyze the incidence and treatment of infection and sepsis during chemotherapy in children with acute lymphoblastic leukemia(ALL) and provide evidences for prevention and treatment of infection. Methods Medical data of 51 children with ALL who received chemotherapy from January 2015 to January 2018 in pediatrics hematology ward of the affiliated Hospital of Southwest Medical University were retrospectively analyzed. Results There were 24 males and 27 females, with first diagnosis age of 1-13(6.96±3.34) years old. The total infection rate was 40.5%(188/464) when taking the number of chemotherapy courses into account; the incidence of sepsis was 14.2%(66/464), and it mostly occurred in high-risk chemotherapy group(19.1%, 31/162) and at the stage of induced remission(22.64%). The positive rate of blood culture in 49 cases was 20.4%(10/49). The primary infection site of sepsis was mainly in lung(24.2%, 16/66). Neutropenia duration was an independent risk factor for sepsis in children with ALL. The detection rate of G-bacteria in blood culture was high, while the use of carbapenem antibiotics could improve the cure rate of sepsis. Conclusion Sepsis mostly occurs in high-risk chemotherapy group and at the induced remission stage, and the lung is the most common site of primary infection.