A medical cavity channel expander is prepared by water absorption resin. The cavity channel expander has great improvements in terms of water absorption capability and water absorption speed especially the water absorption speed so as to greatly reduce waiting time of a patient and be applicable to expansion of all cavity channel surgeries. Moreover the cavity channel expander has a surface with a hyper slippery effect after absorbing water so the cavity channel expander can enter the cavity channel smoothly without any lubricant.
