The thought of “Three No” in the Platform Sutra of the Sixth Patriarch is considered to be the concentrated expression of Hui Neng's thoughts, among which “No-mind” is the most emphasized. This paper illustrates “no-mind” from three different aspects. Firstly, it is the “middle way of Prajna”, and has carried on the thoughts of both Prajna-emptiness and Buddha-nature. Secondly, as a basic characteristic of “the most superior Mahayana” and a basic doctrine of the transcending “Mahayana”, it has inner consistency. Thirdly, it exerts great influence on the later Zen masters and their theories, which expressed the thought “no-mind” with different words, such as “no-doing”, but the meaning is the same.