OO-Method is an object-oriented method for automated code generation. In order to develop a software application by using OO-Method, the analyst must subjectively create the diagrams included in OO-Method. In this task the analyst must invest too much effort. On the other hand, Pre-conceptual Schemas are controlled-language-based diagrams for knowledge representation. Also, Pre-conceptual Schemas are previous diagrams to conceptual schemas and they are designed for automatically obtaining UML diagrams. In this paper, we take advantage of Pre-conceptual Schemas and we propose a set of rules for obtaining OO-Method diagrams from these Schemas. We also exemplify the proposal with a case study.