隋代釋信行所創的三階教，是中國第一個講究實踐佛理教義的宗教團體，三階教的教理多為抄襲，其教義與當時各宗派的信仰多不相合，於開皇二十年首遭敕斷；則天朝，三階教經典因為政治的因素，被判為《偽經》；玄宗時，三階教徒所行之三階佛法，普遍被視為「異端」，其活動屢遭禁止。三階教在隋與唐初的屢次遭禁，使得一千多年來，許多中國佛教徒，不知三階教為何。湯用彤《隋唐佛教史稿》，言三階教在玄宗開元時即宣告滅亡；藍吉富《三階教殘卷•小引》，亦謂三階教於「隋唐間的數次禁遏，而終告滅亡。」本文旨在探討三階教遭禁的原因，兼論三階教並未亡於開元時期。

The SAN-CHIEH-CHIAO founded by HSIN-HSING of Sui Dynasty was the first religion on practicing Buddhistic principle and religious doctrines in China. Most of the Buddhistic principle of SAN-CHIEH-CHIAO copied from other Schools of Buddhism, in addition, its doctrine was inconsistent with others belief at that time. In Kaihuang 20 years, the SAN-CHIEH-CHIAO was abolished by imperial order. During the period of the empress WU ZE-TIAN's ruling, The SAN-CHIEH-CHIAO Sutra was decided into《false Sutras》due to the political factor. The SAN-CHIEH Buddhadharma pursued by the SAN-CHIEH-CHIAO's followers was mostly regarded as 「heresy」, and its activities were often prohibited. Many Chinese Buddhist hadn't known about the SAN-CHIEH-CHIAO for more than one thousand years because it was forbidden many times in Sui Dynasty and at the beginning of Tang Dynasty. TANG YONG TUNG 《The manuscript of Buddhistic history of Sui and Tang Dynasties》said that the SAN-CHIEH-CHIAO had been declared into extinction in the period of emperor Xuan-Tsung Kaiyuan. LAN CHI-FU 《A foreword in the incomplete volume of the SAN-CHIEH-CHIAO》also said that the SAN-CHIEH-CHIAO finally was banned because it was prohibited and contained in Sui and Tang Dynasties several times. This study is to discuss why the SAN-CHIEH-CHIAO had been banned, and about that it didn't perish during the period of emperor Xuan-Tsung Kaiyuan.