The understanding and expatiation to CHAI and DAI images of the commentators in Qing Dynasty(before the 20th century) is the first ring of the endless accepting chain of A Dream of Red Mansions. Their understanding to CHAI and DAI images laid a foundation to people in the furture to a large extent. Their views was abundant and diverse and radiated strong subjective feelings in the process of comment, which of the complex reasons behind their back deserves our considerations.