The author compares the meaning of the literal difference of "Four Greatness" in Mao and Xi era with psychology. After examining the political, social, and economical situation of two eras in literatures, the author discovers Mao's frustration and aggression are from his failure of governance and the confliction with Liu Shao-Qi. Thus, Mao arises the "Cultural Revolution" to maintain his charisma with "Four Greatness". In Xi era, the "Four Greatness" may reflect Xi's strong sense of purpose toward CCP and PRC, or may just reflect his compensation for inferiority complex from childhood with imitating Mao Ze-Dong.