To explore the therapeutic effect of partial splenic embolization of different embolized volumes for idiopathic thrombocytopenic purpura (ITP) and consequent changes of the splenic function.Forty-five ITP patients were randomized into 2 groups to receive splenic embolization with gelatin sponge particles, and the embolized volume ranged between 60% and 80% in the former group (group A), and between 40% and 60% in the latter group (group B).The platelet counts of the patients in both groups markedly increased one week after the operation, and the average count was significant higher in group A than in group B one year after the operation (P0.05).Splenic embolization of different volumes produces similar therapeutic effect on ITP, but more extensive embolization may insure long-lasting effect with better safety and less influence on splenic function.