The aims of this study are to examine the lifetime and educational thought of Dasan Jeong Yak-Yong and to find the significance of meeting and Dasan's educational spirit. Dasan was born on June 16, 1762 and died on February 22, 1836. In general, his lifetime is divided into four periods : ①learning stage(1-28age), ②public service stage(28-39age), ③exile stage(40-57age), ④emancipation stage(57-75age). He systematized the philosophical foundation of practical science of the late Joseon Dynasty. An ideal image of a man to Dasan is a shepherd, who not only keeps his duties of magistrate but also is well qualified as a governor with learning and virtue, and as a teacher to lead people. Therefore, a shepherd is a practician having the whole personality of self-control first and then govern others. The spirit of governor based on practice of the self-control first and then govern others should not be looked down on as the old, and its spirit and lesson should not be overlooked in modern education. Dasan emphasized here and now and service to humanity. His aim was to educate a person to be a good father, mother, son, daughter, friend, and citizen. He believed that every person should strive for the continual development of self until excellence is achieved. The seven principles of teaching and learning which Dasan executed are as follows : ①step by step, ② major, ③fitting, ④practice, ⑤discussion, ⑥collaboration, and ⑦creative activity. It is sincerely hoped that this study on Dasan's Educational Thought will be contributed as a stepping stone of some help to those scholars and students who are interested in new teacher-education of the 21st century.