In Mahābherihārakaparivarta sūtra, ineffability is quite an important approach to delineate “tathāgata-garbha”. Considering the context and the meaning, the term “tathāgata-garbha” should be translated as “the life with tathāgata covered by illusion”. Furthermore realizing the ineffability may lead us to remove “shadow of illusion”, and thus attend dharma-kāya.Through this way, I delineate the tathāgata-garbha. Due to the different endowment, not all the sentient-beings can understand tathāgata-garbha. To overcome the difficulty is the main purpose of this research. Basing on Mahābherihārakaparivarta sūtra, we can find the clues of ineffability which the Buddha left for us. For the novice of tathāgata-garbha,one should abandon one’s defective thinking, because it can not help to go deep into reality. Besides, we should avoid attaching to Buddha's literal meaning and faithfully follow the Buddha’s teaching of tathāgata. To approach to tathāgata, we must practice the Buddha’s teaching. By practicing, we can eliminate illusions and go deep into reality, the tathāgata.