Objective:To investigate the roles of T helper 17(Th17)cells and regulatory T(Treg)cells, interleukin(IL)-17 levels, and IL-6 levels in the pathogenesis of Henoch-Schonlein purpura(HSP)complicated with Helicobacter pylori(HP)infection in children. Methods:Children diagnosed with acute HSP and/or HP infection by the Department of Pediatrics, Xiamen Maternal and Child Health Care Hospital from January 2017 to December 2018 were enrolled in the study.There were 15 children with HSP complicated with HP infection(HSP-HP group), 26 children with HSP(HSP group), and 21 children with HP infection(HP group). Twenty healthy children of the same age over the same period were included in the healthy control group.The proportions of Th17 cells and Treg cells were tes-ted by flow cytometry(FCM), and concentrations of IL-17 and IL-6 in plasma were measured by enzyme linked immunosorbent assay(ELISA).Results:(1)Compared with that of the healthy control group [(1.42±0.63)%], the proportion of Th17 cells in the HSP-HP group, HSP group and HP group [(2.79±0.78)%, (2.04±0.77)%, (2.08±0.86)%] was significantly increased( F=5.271, P<0.05). The levels of IL-17 and IL-6 in the HSP-HP group [(552.16±121.13) ng/L and (12.36±6.55) ng/L], HSP group [(506.39±113.62) ng/L and(11.82±5.01) ng/L] and HP group [(483.14±121.77) ng/L and (10.19±3.87) ng/L] were significantly higher than those in the healthy control group [(302.96±82.83) ng/L and (7.81±2.04) ng/L]( F=13.113, 6.692, all P<0.01). The proportion of Treg cells in the HSP-HP group [(1.35±0.49)%], HSP group [(1.13±0.86)%] and HP group [(1.09±0.65)%] was significantly lower than that in the healthy control group [(2.31±0.83)%]( F=6.983, P<0.05). (2)The proportion of Th17 cells and the level of IL-17 in the HSP-HP group were significantly higher than those in the HSP and HP groups(all P<0.05). There was no significant difference in the proportion of Th17 cells and the level of IL-17 between the HSP group and HP group(all P>0.05). There was no significant difference in the proportion of Treg cells and the level of IL-6 among the HSP-HP group, HSP group, and HP group(all P>0.05). Conclusions:The imbalance of Th17/Treg cells in peripheral blood may contribute to the development of HSP-HP, HSP and HP infection in children.High expression of Th17 cells and their related IL-17 is more prominent in children with HSP-HP.