The invention discloses a method for extracting hirudin form leech saliva. The method includes the following steps of a), placing leeches in a container to allow the leeches to be hungered sufficiently, inputting inductive substances to the leeches to allow the same to absorb fully, adding vomitives to allow the leeches to spit the saliva in bodies, taking out blood-sucking leech living bodies to return to a rearing pond to feed continuously, and meanwhile, collecting hirudin crude product liquid in the container; b), freezing above hirudin crude products, adding into precooled cold acetone, stirring prior to placing in a refrigerator for setting overnight, sucking supernatant acetone the next day prior to centrifuging, adding a trichloroacetic acid solution, and centrifuging to remove residues to obtain concentrated liquid; c), eluting the above concentrated liquid with an anion exchange column chromatography method, and performing gel filtration chromatography to obtain finished products. The method has the advantages of reasonable process, convenience and practicability in operation, good quality stability of the finished hirudin products and high yield, one-time pillage on the leeches with a traditional method can be avoided, wild resources of the leeches are protected, and development of leech farming is driven.