<p>The <i>Shoulengyan jing</i> 首楞厳経 is known as a Chinese apocryphal sutra that was composed in the beginning of the 8th century. Recently this sutra has attracted much attention in the study of the controversy between Ekayāna and Triyāna theories in Japan.</p><p>In this study, I research fragments of Hongyan's 弘沇 <i>Da foding jing shu</i> 大仏頂経疏, a commentary on the <i>Shoulengyan jing</i>, and other commentaries. As a result, I point out that the <i>Shoulengyan jing</i> is accepted as an Ekayāna sutra, and is based in the context of criticizing the Triyāna doctrine.</p>