Abstract： Objective To investigate the roles of thrombopoietin level and reticulated platelet percentage in the pathogenesis of idiopathic thrombocytopenic purpura. Methods The level of thrombopoietin and the percentage of reticulated platelet in 50 ITP patients and 30 healthy controls were tested by virtue of sandwich enzyme-linked immunosorbent assay and flow cytometry respectively. The peripheral platelet count was conducted with on automatic hemocyte analyzer. Meanwhile, the bone marraw megakargocget, using general staining method, was counted directly under microscope. Results Compared with the control group, the counts of platelets in ITP patients significantly decreased (P <0. 05) (30.65±18.34)×109/L and (222.60±45.32)×109/L; the percentage of reticulated platelet(28.11±14.08)% and 8. 19±2.46)% and megakaryocyte (132.58±73.95)/4 cm2 and (20. 10±7.64)/4 cm2 in ITP patients notablely increased (P < 0.05). However there was no apparent difference of the level of thrombopoietin between ITP patients and control group (76.65±32. 50) ng/L and (75.36±26. 32) ng/L (P>0.05).Conclusion Detecting the level of thrombopoietin in associated with the percentage of reticulated platelet in the patients with idiopathic thrombocytopenic purpura helps improve the diagnosis and clinical therapy of idiopathic thrombocytopenic purpura.