Objective: To study the correlation between peripheral blood CD4+CD25+Treg levels and systemic inflammatory response in patients with sepsis. Methods: 36 children who were diagnosed with sepsis in Children’s Hospital of Hebei Province between June 2014 and December 2016 were selected as sepsis group, and healthy volunteer children who received physical examination during the same period were selected as control group. Peripheral blood was collected to determine the content of CD4+CD25+Treg cells, and the serum was collected to determine the contents of the inflammatory mediators and oxidative stress products. Results: Peripheral blood CD4+CD25+Treg cell level in sepsis group was significantly higher than that in control group. Serum ICAM-1, TNF-α, IL-1β, CRP, PCT, LPO, MDA and AOPPs levels in sepsis group were significantly higher those in control group; serum ICAM-1, TNF-α, IL- 1β, CRP, PCT, LPO, MDA and AOPPs levels in sepsis children with high Treg level were significantly higher than those in sepsis children with low Treg level. Conclusion: Increased levels of CD4+CD25+Treg cells in patients with sepsis can activate systemic inflammatory response and oxidative stress response.