一般認為，宋初南方降臣在政治上遭到歧視性的待遇，南方文士也必須靠科舉才能在仕途上有所表現，但這只是事實的一部分。本文探討宋初降臣中一個特殊群體：徐鉉及其後學。本文指出，徐鉉入宋後得到以李昉為核心的北方文士不同尋常的敬重，這群北方文士更不遺餘力地舉薦徐鉉後學。這使他們獲得較多入仕中央的機會。不過，太宗對江南降臣的猜忌，導致徐鉉晚年遠貶攽州，進一步使李昉、徐鉉後學的關係產生變化。然而，徐鉉後學並未從此沉寂，其中杜鎬、陳彭年、王欽若，在真宗朝獲得君主的信任，他們靈活利用徐鉉崇拜唐玄宗的政治理念，而為真宗大中祥符時代的神道禮儀提供了部分思想資源。徐鉉後學之政治影響力，也到達前所未有的高度。

This article discusses a special group of people: Xu Xuan(徐鉉) and his disciples’ official careers and their influence on political affairs. We usually consider that surrendering subjects in the south had been discriminated during the early Song. Xu Xuan, having most brilliant scholarship among the intellectuals, however, earned respect and admiration from the nucleus among the north literati headed by Li Fang(李昉), and therefore Xu Xuan and his disciples, on the one hand, had more chances to enter the court than other surrendering intellectuals. On the other hand, after Xu Xuan’s death, his disciples, Du Hao(杜鎬), Chen Pengnian(陳彭年), and Wang Qinruo(王欽若), gained Emperor Zhenzong of Song’s trust. They utilized their teacher’s political concept and successfully convinced Zhenzong to follow the example of Xuanzong of Tang in the era of “The Auspicious Talisman of Great Centrality” (大中祥符). Xu Xuan’s disciples’ political weight thus had increased up to the unprecedented level.