Knowledge is the ladder for human progress and the first productive force of modern society. The reproduction, dissemination and regeneration of knowledge can only be achieved in actions, and translating is naturally a type of knowledge action. However, people used to merely focus on the structured knowledge transferred in translation, putting translation in a subordinate position, which has shadowed its function in terms of knowledge reconstruction and innovation, and ignored the contributions of translation studies to the human knowledge. From the perspective of modern knowledge science, translational knowledge is not just structured knowledge rendered by translation, but can be knowledge reconstructed through translation. In addition, it can be thematic knowledge concerning the topic of translated knowledge. For this reason, this paper proposes that translational knowledge is a complex entity which consists of thematic, reconstructed as well as structured forms. Only when we clarify this threefold form of translational knowledge and their internal logic, can we reveal the true value of translation in knowledge accumulation and (re)production.