Objective: To prepare Pingyangmycin gelatin microspheres (PYM-GMS) for carotid artery embolization therapy and to study the release characteristics in vivo and in vitro. Methods: PYM-GMS was prepared by optical double-phase emulsified condensation polymerization. Through UV-spectrophotometer drug content and encapsulation rate were measured. The characteristics of drug release in vitro which could simulate the actual state in vivo were tested by HPLC. Three ways of vein drop, artery perfusion and artery embolization were contrasted. Under the supervision of X-ray, PYM-GMS were perfused into the external carotid artery of rabbits by superselective artery embolization. Blood samples were tested at different time and analyzed statistically. Results: The roundness of PYM-GMS was 1.02±0.005. The mean diameter was 85.6 (m, 78% of them ranging from 50(200 (m, which fitted the use of embolization. PYM content and encapsulation rate were 6.8% and 91.3% respectively. 70% of the drug was released in 3 h in the simulated environment in vivo and total drug was released after more than 6 h. After artery embolization with small dosage of PYM-GMS, the local drug concentration was 8 times higher than the blood drug concentration and the high level of local drug concentration was kept for more than 120 min. Conclusion: External carotid artery embolization with PYM-GMS, which significantly reduced the circulating drug level and employment dosage, could prolong the duration higher drug concentration and suit the purpose of targeted tumor therapy.