The present invention discloses a preparation method of bloodsucker extract, in which the bloodsucker is added with water and homogenized, and then the bloodsucker extract is obtained by controllable enzymolysis, organic solvent precipitation, ultrafiltration and anion-exchange chromatography. The bloodsucker extract can be adopted to prepare a medicine with anticoagulation, thrombolytic ability, inhibition on platelet aggregation and neuroprotection effect. The present invention, according to the modern technological requirements of Chinese medicine, adopts the technology of controllable enzymolysis for extracting the peptide component, the separating technology of ultrafiltration and gel chromatography for purification further, and the biological pharmacy technology, thus obtaining the extract with higher pureness and stronger activity than the traditional bloodsucker extract. The method breaks through the bottleneck of the traditional animal medicine in extraction and separation, solves the problem of the traditional animal medicine that the amount of raw powder is large and the taste is fishy, improves the activity and quality controllability of the animal medicine extract further and greatly improves the utilization rate of medicinal materials.