The meanings of the tacit knowledge and the codified knowledge are described, and the two concepts are compared in detail. Further more, it is demonstrated that there is an inseparable relation between the tacit knowledge and the codified knowledge whether they are in static state or dynamic use. The implications of the inseparable relation for understanding and dealing with some knowledge problems, such as the knowledge transfer and sharing, the tacit knowledge storing and searching, and the knowledge codification are discussed.