'Haein' in 'Haein-sa' comes from 'Haein samadhi' of the Avatamsaka Sutra which means that reason of everything is revealed in agony-less mind just like figures of whole things appeared on the quiet sea. And 'Haein' points out the world of 'as it is', the world seen by true, wise eyes, the world of objective thoughts, and the world of eternal Truth.

Haein-sa was founded by Suneung Sunim and Ijeong Sunim under the full support of the Silla royal family in the 3rd year of King Aejang (802 AD), the 40th king of the Silla Dynasty to elucidate philosophy and thought of the Avatamsaka School. In 930 ca, early period of Koryeo, Master Heuirang remolded Haein-sa under support of King Taejo Wanggeon and raised BuddhaDharma highly. In 1488 AD, Hakjo Sunim rebuilt Haein-sa in large scale under support of Queen Insu and Queen Inhye. After that, rebuilding and destroying by fire were repeated, and the Hall of Great Tranquility that is the center building and other buildings at present were built in 1818 AD.

Four dynasties of Silla, Later Three Kingdoms, Koryeo, and Joseon rising and disappearing, Haein-sa has experienced national disasters such as Japanese invasion in 1592, colonization by Japan in early 20 century, and the 6.25 Civil War for a long time.
However, Haein-sa has been standing firmly and keeping it's purity through harsh history.

Haein-sa, the First Dharma Jewel Monastery, is the foundation temple of Avatamsaka School of Korea and the temple that the Tripitaka Koreana is enshrined. The Tripitaka Koreana is integration of Korean people's faith. Haein-sa is the spiritual shelter of Koreans, the lantern of wisdom brightening this land,
and a sacred place of Korean Buddhism.