Primary immune thrombocytopenia (ITP) is an autoimmune disease with an incidence about 4~5/100000 in children. Most children with ITP (80% - 90%) return to normal within 12 months after diagnosis, but a few (10% - 20%) have thrombocytopenia for more than 1 year, turned into chronic ITP (CITP). The pathogenesis of CITP is not clear. It is believed that under the background of susceptible genes in children, the destruction of monocyte-macrophage system caused by autoimmune antibodies produced by infection and immune disorder results in thrombopenia. According to the recent research on ITP, this paper reviews the diagnosis, predictive factors and treatment of CITP.