西藏因青藏高原的地理環境和不利漢人居住往來的氣候，所以在中國歷代並沒有和西藏有官方性質的接觸，直到松贊幹布統一吐蕃開啟和唐朝政治、文化交流。在清朝時在西藏設立駐藏大臣，並頒布「欽定藏內善後章程」二十九條，明確規定中央和西藏地方關係。但至中華民國成立初期政局紛亂，中斷中央對西藏的治理。 國民黨在國共內戰挫敗，並撤退至台灣。1949年中共政權在北京成立，「昌都之戰」後中共開始治理西藏，並成立西藏自治區。但因西藏的宗教、文化的不同而產生隔閡和衝突。2006年青藏鐵路興建完成後，改變中共對西藏的治理。達賴喇嘛之前曾一度肯定青藏鐵路對西藏的開發將是有目共睹，但之後又改稱，青藏鐵路不利於西藏。青藏鐵路究竟是一把北京政府直插西藏的利刃，還是一條改善西藏人民生活的「幸福線」？就如同達賴前後兩種看法般眾說紛雲。 但是青藏鐵路的興建對西藏的影響是不可否認的，本論文將以政治影響、社會變遷、經濟發展三方面來探討。 / Tibet is a region on the Qingzang Plateau that inclement and precipitous surrounding. Official communication of Tibet with ancient China started from Tang dynasty. In period of Qing dynasty, the emperor set up Ambans to Tibet, and issued a 29-point decree which appeared to tighten Qing control over Tibet. The rule is interrupted during the period of Republic of China. And Dalai Lama ruled Tibet without Chinese interference. The People's Republic of China was established and governed Tibet after Battle of Chamdo. There are many conflicts between Han and Tibetan due to difference culture and religion. Furthermore, China government decided the construction of Qinghai-Tibet Railway. The railway is very meaningful and influenced on Tibet. This essay will be discussed and investigated the impact in the three terms of politics, society, and economic.