Abstract: 　Objective　To investigate the changes in plasma myeloperoxidase (MPO), malondialdehyde (MDA), superoxide dismutase (SOD) and total anti-oxidant capability (T-AOC) of Henoch-Schönlein purpura in children. Methods　A total of 80 HSP children hospitalized from November 2013 to April 2014 were selected including 40 cases of arthritis type, 20 cases of abdominal type and 20 cases of nephritis type (HSPN). Meanwhile, 16 healthy check-up children were selected as controls. Plasma MPO, T-AOC levels were detected by chemical colorimetry and MDA levels were detected by thiobarbituric acid colorimetry. Plasma SOD levels were measured by hydroxylamine method. Furthermore, 24-hour urine protein and other hematological indices were routinely tested. Results　The plasma levels of MPO, MDA, SOD and T-AOC were significantly different among control group, arthritis type group, abdominal type group and HSPN group (F=24.22-126.99, all P=0.000). In comparison to other three groups, the levels of MPO and MDA were significantly increased and the levels of SOD and T-AOC were significantly decreased in HSPN group (P<0.05). Compared with control group, the levels of MPO and MDA were significantly higher and the levels of SOD and T-AOC were significantly lower in arthritis and abdominal type groups (P<0.05). The levels of MPO and MDA in HSPN group were significantly positively correlated with 24-hour urine protein (r=0.695, 0.559; both P<0.01). Conclusions 　The imbalance between oxidation and antioxidant system exists in children with Henoch-Schönlein purpura.