馬列主義揭示無產階級政黨必然會帶領群眾走向共產天堂，這樣的「目的論」賦予了共產黨作為無產階級先鋒隊統治上的合法性。1978年以來，中共為了發展經濟改革而多次進行意識型態的修正，2000年以前中共所修正的意識型態都謹守在社會主義框架中，自我定位為工農階級政黨，但「三個代表」允許資本家入黨，卻將合法性基礎轉向了其他社會階層。 為什麼中共要提出「三個代表」，以及為何提出的時間點會在2000年？本文認為要從經濟結構和領導互動兩個變數來解釋。市場化的改革造成中國大陸經濟和社會的變動，私營經濟發展迅速、公有制經濟的優勢地位受到挑戰、紅色資本家人數上升，這些變化使理想與現實嚴重脫節。由於延續市場化路線在1990年代後已成為領導人的既定政策，加上前蘇聯因為脫離群眾而崩潰的經驗，使中共面對經濟社會變動時，選擇調整意識型態以符合現實需求。 1998年以後，經濟社會的變動更形劇烈，私營經濟負擔稅收、產值與就業的功能顯著提升，學界發表大量調研報告，加重了領導人的壓力，調整意識型態已經勢在必行。合法性基礎轉變以後，中共必需以政績尋求支持，並解決民眾需求。然而當「由下而上」的民意日趨重要時，勢必在未來衝擊「由上而下」的一黨專政體制。 / Marxism-Leninism theory claims that proletariat party will inevitability lead the people to arrive the paradise of communism. Such the “teleology” gives the legitimacy on as proletariat vanguard for Communist Party. Since 1978, the CCP revised ideology for many times to develop the economic reform. Ideology revised by CCP before 2000 was kept in the frame of socialism; the CCP positioned oneself as the class parties of workers and peasants. However the “Three Represents” allows capitalists to join the party, and turns the foundation to other social strata. Why did the CCP propose the “Three Represents” in 2000? I think there are two factors: the economic structure and interactions between the senior level. The market-based reform causes the economical and social change; like the rapid development of private economy, the challenge in the advantage of public economy, and the red capitalist's number rises. Which changes make ideal and reality disconnect seriously. The leaders extend the market-based policy, and the experience of the Soviet Union collapse, make the CCP in the face of the change of economy and society, choose to adjust ideology in order to accord with the current demand. After 1998, the violent change in the economic society appears even more violently, became that tax from private economy, the functions of the growth of output value, employment improve apparently, a large number of research reports were delivered by educational circles, has been imperative for the leader's to adjust ideology. After the transition of the legitimacy foundation, the CCP has to seek the support from the people by achievement in politics, and needs the demands of people. From top-to-bottom dictatorship system of one party will certainly be assaulted, when the “bottom-to-top” opinions of people become more important in the future.