Children with Coronavirus Disease 2019(COVID-19)were reported to show milder symptoms and better prognosis than their adult counterparts,but the difference of immune response against SARS-CoV-2 between children and adults hasn't been reported.Therefore we initiated this study to figure out the features of immune response in children with COVID-19.Sera and whole blood cells from 19 children with COVID-19 during different phases after disease onset were collected.The cytokine concentrations,SARS-CoV-2 S-RBD or N-specific antibodies and T cell immune responses were detected respectively.In children with COVID-19,only 3 of 12 cytokines were increased in acute sera,including interferon(IFN)-γ-induced protein 10(IP10),interleukin(IL)-10 and IL-16.We observed an increase in T helper(Th)-2 cells and a suppression in regulatory T cells(Treg)in patients during acute phase,but no significant response was found in the IFN-γ-producing or tumor necrosis factor(TNF)-α-producing CD8+T cells in patients.S-RBD and N IgM showed an early induction,while S-RBD and N IgG were prominently induced later in convalescent phase.Potent S-RBD IgA response was observed but N IgA seemed to be inconspicuous.Children with COVID-19 displayed an immunophenotype that is less inflammatory than adults,including unremarkable cytokine elevation,moderate CD4+T cell response and inactive CD8+T cell response,but their humoral immunity against SARS-CoV-2 were as strong as adults.Our finding presented immunological characteristics of children with COVID-19 and might give some clues as to why children develop less severe disease than adults.