Abstract:This experiment has proven that the drug Naomaitong can synchronously increase the blood flow of both dog‘s internal caroid artery and vertebral artery and also can antagonize the decrease of blood flow of both arteries caused by pituitrin. The increase of blood flow of both internal caroid artery and vertebral artery due to administration of Naomaitong (1.2g/kg) through the dog‘s duodenum is approximately equal to the increase of blood flow of both arteries resuiting from the intramuscular injection of papaverine (1mg/kg). Besides, the dosage of Naomaitong is positively correlated to the effect and action of the drug.