During the one hundred years and more from the beginning of the 18th century to the beginning of the 19th century, about 16 Chinese doctors, at the invitation of Japanese, went to Japan successively by trade ships to practice medicine and teach Chinese medicine. They also conducted academic exchanges with Japanese doctors. Because both the Japanese authorities of that time and the emperor of Qing dynasty implemented the policy of closing the country, they could only do things in certain areas within limited time. By consulting a vast amount of data and following the footprints of some of the Chinese doctors in Japan, the author has got things into shape about the comings and goings of the doctors who went to Japan during the century and their activities, with the stressed point laid on the achievements of such influential doctors as Zhu Laizhang, Zhu Zizhang, Zhou Qilai, Zhao Songyang, Li Renshan, Hu Zhaoxin and so on.