本文試圖從「文學反映社會」的視角來分析牛僧孺的《玄怪錄．郭代公》，挖掘其「以賢明訓教不肖」的意旨。小說以漁肉鄉民的「烏將軍」影射唐代的藩鎮亂象，耆老的順從反映了朝廷的姑息，而「郭元振」為民除妖則寄寓了百姓對懲惡治亂的期盼。末尾敘述郭元振娶美妾、天定功業，傳達民心向背及對躁進者的警勉；既有對昔日大唐盛世的嚮往，也有對中晚唐現況的檢討。另一方面，將〈郭代公）「示藩鎮以箴規」的旨趣與牛僧孺治理藩鎮的理念進行對照，可知牛相雖不主削藩，但絕非姑息；而小說中的除妖情節只能視為「筆誅」、「勸化」不能逕自解讀為削藩。牛作此文，一則渲洩其對亂象的不滿，二則希冀藩鎮能見賢思齊，讓國家在安定中求進步。

This thesis tries to analyze Niu SengRu's "Xuanguai Lu,Guo Daigong" in the viewpoint of "Literature reflects the society", and then finds its purport was that "gentleman give villain a lecture". In this fiction, General Wu who hectored villagers was insinuated as the rebellious military governor in the Tang Dynasty, the elder who rolled with the punches was a mirror of the over-lenient court, Guo Yuanzhen who destroyed the monster brought the masses a hope of punish evil. The last of fiction described that Guo Yuanzhen married a beautiful concubine, and all his exploits are the will of Heaven, it shows that where the popular will inclines, moreover, it gives the authority-chaser an admonition. On the further meanings, this fiction is not only full of the yearning for the past glorious period of Tang Dynasty, but also has criticism to the situation of the middle-late period of Tang Dynasty.On the other hand, the keynote of 'Guo Daigong' is "an admonition to military governor", when we contrast it with Niu SengRu's political idea for military governor, we could find that, although Niu SengRu didn't advocate cutting the claws of military governor, he never advocate rolling with the punches; the plot about eliminating the monster is only interpreted as "pen-denouncing" and "exhorting", rather than cutting the claws of military governor. To infer the reason why Niu SengRu wrote this fiction, first, to let his complaint about the social disorder off, second, to hope the military governor could seeing another better than oneself, one tries to equal him, and wish the country could make progress in stable situation.