天台宗不只教相判釋完備周詳，成為中國佛教最重要的判教理論之一，觀行法門更是包羅廣博，最稱詳盡。但是尚欠缺對其所提到的所有法門之全盤彙整歸納。又一般論天台教觀多以四教、三觀為要，但是二者之說並非智者大師一開始提出的。一般所重之圓教法門含四種三昧，四種三昧在智者大師前後講著亦呈現不同屬性。凡此種種皆是確切了解天台宗之重要課題。本文即根據智者大師之前期著作，一一解析並歸納其修行法門，進而回應上述課題，顯明四教、三觀思想之發展、早期四種三昧之性質，以及如以四教劃分，各法門應判屬何教等。依筆者研究所得，智者大師最早講《方等三昧行法》，原只屬空觀法門。《釋禪波羅蜜》承繼其師慧忍之說，參照《大智度論》及各種經論，組織完備之次第修行體系。其中提到三觀，仍以空觀為主要觀法。《法華三昧懺儀》之觀法亦屬空觀，與《方等三昧行法》所言均非圓教觀法，不同於《釋禪波羅蜜》所判，可說屬於別、圓二教法門。《六妙法門》在智者大師講述時，原無意將之當成化儀不定止觀之代表作，此說法可能是灌頂所提出的。書中次第言空觀、假觀、直觀如來藏心（如別入圓教觀），進至圓觀，可見三觀說之初期發展。「一心三觀」之說則尚未出現。至於「四教」則在智者大師前期時代作品均未提及。

Both of the "theory of classification of teaching" and practice ways of T'ien-t'ai Buddhism are very copious and complete. But there is still no paper which gathered and showed all of the practice ways of T'ien-t'ai Buddhism. Besides, it is known that "Four Teachings" (四教) and "Threefold Contemplation" (三觀) are the essentials of T'ien-t'ai Buddhism. But they were not established by Zhi-yi (智顗) at the beginning "Perfect-teaching" (國教), which is noticed the most, includes "Four Forms of Samadhi" (四種三昧). The characteristics of "Four Forms of Samadhi" were different between Zhi-yi's books of earlier and later stage. These all are important topics to know well about T'ien-t'ai Buddhism. This paper will collect all the practice ways of T'ien-t'ai Buddhism by analyzing all the Zhi-yi's books of his earlier stage and shows the development of "Four Teachings" and "Threefold Contemplation," the characteristics of "Four Forms of Samadhi," and each practice ways belongs to which teaching of "Four Teachings." According to my research, the practice ways of "Fang-dang Samadhi" (方等三昧) belongs to "Contemplation of Empty" (空觀). In "Shi-chan-bo-luo-mi" (釋禪波羅蜜), Zhi-yi developed a complete system of practice, based on the theory of his teacher Hue-si (慧思), "Da-tsu-du-lun" (大智度論) and many scriptures "Threefold Contemplation" was mentioned in "Shi-chan-bo-luo-mi," but the major way of contemplation in was still "contemplation of Empty." The way of contemplation in "The Ritual of Lotus Samsdhi" (法華三昧懺儀) belongs to "Contemplation of Empty" too. Both of the ways of contemplation of "Fang-dang Samadhi" and "The Ritual of Dharma Lotus Samadhi" were not practice ways of "Perfect-teaching." But they became to be practice ways of "Separate-teaching" (別教) and "Perfect-teaching" in "Shi-chan-bo-luo-mi." The statement that "Six Marvelous Practice Ways" (六妙法門) was the representative work of "Indefinite Way of Samadhi and Contemplation" (不定止觀) was not made by Zhi-yi, but perhaps made by Guan-ding (灌頂). The evolution of the theory of "Threefold Contemplation" appeared in "Indefinite Way of Samadhi and Contemplation." But the theory of "Threefold Contemplation in One Single Mind" (一心三觀) didn't appear till now. The saying of "Four Teachings" (四教) wasn't mentioned in all Zhi-yi's books of his earlier stage.