長安與洛陽是白居易一生中兩個重要的居住地，但是對於兩京，白居易詩卻呈顯出截然不同的情感意趣：從城市實踐理論的角度來說，他以「俯瞰」遠觀的姿態對待長安，覺得那是一個陌生殊異的空間；而以「行走」穿梭之身融入洛陽，覺得這是一個樂園終老的地方。他用疏離的態度所描寫的長安，很少出現自己的身影，是一個逸離長安城的他者；相反地，他大量反覆地歌詠自己在洛陽城中狂遊的過癮姿態，是一個居遊洛陽的名家。本文先以城市實踐現象的差異比較為基礎，討論白居易長安詩的疏離陌異與洛陽詩的居遊成癮。再透過心理學的防衛機轉理論，分析白居易在兩京詩中寓含的不安焦慮與幾種不同的自我防衛作用，以及最終的自我療癒。因而呈現生命價值序位調整前後，詩人與都市環境品質之間，對應關係的變化，以及心理隨之療癒的歷程。

Chang-An and Lou-Yang were two important dwelling places of Bai JuYi. But he showed totally different attitudes and affections towards these two cities. From the perspective of urban practice, he ＂overlooked＂ Chang-An and took it as a space of strangeness. However, he ＂walked through＂ in Lou-Yang, taking it a paradise for permanent dwelling place. He wrote Chang-An in a tone of alienation rarely involved in the scene, as an onlooker of Chang-An. On the contrary, he repetitively claimed his wild entertainment as an addicted player in Lou-Yang. This paper is based on the basis of urban practice, discussing the alienation in poems of Chang-An and the addiction of poems in Lou-Yang. Then, with the defense mechanism and composition in psychology, I analyze the anxiety and self-defense of Bai JuYi’s poems of two cities, and in the end, the final curing. When the priority of life value was altered, the relationship between the poet and the quality of environment was undergoing a changing process.