Hyaluronidase (HAase) is a general term for enzymes that can hydrolyze hyaluronic acid. It is an enzyme that can reduce the activity of hyaluronic acid in the body, thereby improving the fluid permeability in tissues. When used in the human body, it can temporarily reduce the viscosity of the intercellular matrix, promote subcutaneous infusion, locally accumulated exudate or blood to accelerate diffusion and facilitate absorption, and is an important drug dispersant. Clinically used as a drug penetrating agent to promote drug absorption, promote local edema or hematoma dissipation after surgery and trauma. Human HAase consists of 435 amino acids which contains a signal peptide of 1-21 amino acids and it shares 74% and 75% amino acid sequence homology with mouse and rat respectively. The activity assay of recombinant human HAase was measured by its ability to hydrolyze the substrate hyaluronic acid. The rhHAase was diluted to 0.5 ug/ml in 8.46 mM NaH2PO4, 11.54 mM Na2HPO4, 77 mM NaCl, 0.1 mg/ml BSA, pH 7. 50 ul 0.5 ug/ml rhHAase was added into the microplate and start the reaction by adding 50 µL of 0.3 mg/ml substrate which was diluted in 300mM NaH2PO4, pH 5.35. Incubated at 37 °C for 5min and add 50 ul reaction mixture to 250 ul 1 mg/ml BSA in 24 mM sodium acetic, 79 mM acetic acid, pH 3.75. Incubated at room temperature for 10min and read at a wavelength of 600 nm. The specific activity of recombinant human HAase is >30 pmol/min/µg.