In this paper, the author portrays the knowledge involved in human consumption, investment interest and production activities. Then he further describes the intangible knowledge field and finally brings out different methods of qualitative knowledge evaluation. At the end, he does finish the argumentation related to the difficulties in separately and objectively processing of quantitative knowledge evaluation. However, he doesn't deny the importance of the quantitative knowledge evaluation. On the contrary, he tries to point out that one has to incorporate this evaluation into the synthetic evaluation of its corresponding investment project, and recognize the difficulties in separately and objectively processing while engaging in quantitative knowledge evaluation.