”Zhijan” had been once highly evaluated and popular but gradually lost due to the criticism by Zhuzi, Zhang Chi and Lü Zuqian. Not until the Ming Dynasty, Cheng Minzheng found and published it again. However, due to his respect of Zhuzi, his edition had those passages doubted by Zhuzi deleted. Cheng's edition remains the most popular one whereas there is another edition in the Sikuquanshu. For the presently available evidence there is no sign that the latter edition is earlier than Cheng's. I then make a detail analysis of the content of Zhang Nanxuan's Preface and proved that it was written around the second to the fourth year after Hu Wufeng's death. It also shows how much Nanxuan understood and accepted the teachings in ”Zhijan”. It also shows how Zhuzi understood and accepted ”Zhijan” when he joined and defended Nanxuan in the latter's responses to the criticisms from other Hu Wufeng's disciples on his Preface. Finally this paper proved that the first paragraph criticized in Zhuzi's ”Doubts on Zhijan” was the first paragraph of ”Zhijan”. It proves that the basic ideas of Hu Wufeng's philosophy are 'Hsing (Nature) is the most basic principle of the Universe' and that 'Hsin (Mind) concretizes Hsing'. The paper then gives a rough sketch of how the first chapter of ”Zhijan” is related to latter chapters to show the basic structure and logic of the whole book.