宋代天臺懺法除了為求自身罪滅、觀行成就或往生淨土而行懺外，對「代眾生懺悔」的懺他精神，較隋唐時期也益加重視，此應是受到晚唐以來政治動亂及宋朝建國後，除社會經濟困頓之外，又相繼受到遼、夏、金等北方民族的覬覦，使得國家百姓無一日不處在內憂外患之中所受到的影響。 因此，遵式大師認為，為使自己及芸芸大眾能安心於佛法上修行，應先消除所共之惡業，進而了達因果緣起，方能成就解脫。是以大師於懺儀中提出，行者於披陳懺悔時，應心念自己及眾生無始來常為重罪所障，是故於諸佛菩薩座前應普為眾生歸命懺悔，由此而融入了代眾生懺悔的修行。 然而，在因果平等的法則之下，代眾生懺悔或受苦的理論將如何成立？我輩凡夫又應如何落實此菩薩精神？ 於此，筆者首先從經典之中溯源「代眾生懺悔」之依據；繼之，從天臺教觀角度探討「一念三千」、「三因佛性」等圓頓思想，以作為「代眾生懺悔」之立論基礎；最後，就遵式大師之著作整理出懺悔、放生、誡酒肉五辛及施食等行法，探討如何以天臺之觀行配合「代眾生懺悔」之實踐，一方面達到幫助眾生令其離苦得樂之願行，一方面則在實踐的過程中，能對緣起諸法有更深刻的體會，早日證得實相。

In the Song dynasty, the Tiantai school placed more emphasis on “repentance on behalf of sentient beings” than it did in the Sui and Tang, with the exception of repentance for the purpose of seeking individual expiation, meditative attainments, or rebirth in the Pure Land. This may be due to the negative effects on the lives of common people of several factors, including political unrest at the end of the Tang, social and economic problems in the Song, and rule by northern peoples under the Liao, Xia and Jin dynasties. Zunshi believed that the best way for himself and Buddhist worshippers to become steadfast in their practice was to first remove all of their evil karma, then understanding cause and effect, they would attain liberation. Zunshi mentions in one of his ritual guides that when the practitioner recalls his misdeeds, he should bring to mind the fact that he and all beings have been creating karma since beginningless time, and therefore one should seek repentance in front of an image of a buddha or a bodhisattva. It is in this respect that Zunshi undertakes the practice of “repentance on behalf of sentient beings.” However, because cause and effect applies equally to all, how can the theory of “repentance on behalf of sentient beings” be established? In this regard, the author first seeks the textual origins of the concept of “repentance on behalf of sentient beings,” then, in terms of Tiantai doctrine and meditation, takes the perfect and sudden teachings of “three thousand in one thought,” and “three causes in Buddha-nature,” as the theoretical foundation for “repentance on behalf of sentient beings.” Finally, on the basis of Zunshi’s practices of repentance, release of animals, and exhorting others to vegetarianism described in his writings, the author explores ways in which Tiantai doctrine and meditation can be matched with the concept of “repentance on behalf of sentient beings”: on the one hand, one practices the vow of helping beings to abandon suffering and attain happiness; on the other, in the process of this practice, the practitioner gains a deeper understanding of dependent origination, bringing the practitioner closer to the ultimate goal.