Around the Xinhai Revolution，When facing the unprecedentedly grave national and social crisis，Mr. CAI Yuanpei was committed to the national cause of preventing China from collapse and rescuing the people from untold miseries. Mr. Cai tried to develop social education to cultivate Chinese with “intact personalities”，“strengthen Chinese people’s understanding of democratic and republican spirit”. He regarded social education as the historical mission and responsibility of New Citizen to empower our ethnicities，and save China. Whether in office or retired，Mr. Cai devoted his whole life to consistently exploring the theories of social education. He made great efforts in practicing in order to build a diversified and far-reaching modern social education system.