In this paper, we first construct the discourse knowledge structure of education in different disciplines so that the knowledge points in a certain cross-cutting area between different disciplines are finite sets called knowledge domains, and we use the network of the discourse field system to characterize the logical relations in the knowledge space. Secondly, by defining the elements of hypertext as a triadic structure, a specific chain of dependencies is constructed by combining the hypertext structure with the knowledge space. Finally, we conducted a comparative analysis of the knowledge structure of educational discourse in various disciplines. The results show that among 45 knowledge states, 15 attributes corresponding to the whole column have all 0 information values and the knowledge structure model based on the knowledge space can master the corresponding effective skills of students in different disciplines, which indicates that it realizes this learning process of knowledge learning from point to point, from concrete to abstract, and from part to the whole under different disciplines. This paper examines the use of discourse in various knowledge structures, which may provide insights into the teaching of English academic writing in China.