The invention belongs to the field of medicines, and particularly relates to an application of an icaritin 
hydrate for preparing a 
medicine capable of inhibiting a STAT3 (
Signal Transducer and Activator 3 of Transcription) 
signal pathway and preventing and curing an oral 
carcinoma, in particular to the application of the icaritin 
hydrate of a formula I for preparing the 
medicine capable of inhibiting the STAT3 
signal pathway. The icaritin 
hydrate of the embodiment of the invention can inhibit the STAT3 and the 
protein phosphorylation of an upstream pathway JAK2 (
Janus Kinase 2) of the STAT3 inoral 
carcinoma cells, accelerates autophagic 
vacuole to be increased, accelerates an 
autophagy-related labelled 
protein to be transformed to LC3 (light chain)-II from LC3-I, increases the expressionof BECN1 and ATG9 proteins, and reduces the expression of an 
autophagy-related labelled 
protein p62 / SQSTM1. The invention takes an amphipathic block high-molecular 
polymer as a carrier to prepare an icaritin hydrate nanometer 
medicine preparation, the water 
solubility of the medicine is enhanced, encapsulation efficiency is 80% and above, an effect on inhibiting the oral 
carcinoma is better, and in addition, biotoxicity is small.