The schemes generating process of conceptual design is the most crucial part of the process of conceptual design, it is better for understanding the designer's intent process, transferring and accumulating design knowledge with this process, in order to analyze the schemes generating process of conceptual design effectively, this paper takes conceptual design for crane hoisting mechanism for an example, which describes the schemes generating process by using zigzag mapping method and proposes the principle of conceptual design based on directed graph model ,with using metamodeling technology, directed graph model can be applied to prototype system developed by GME, this prototype system provides a simple tools for the process of conceptual design and records the schemes generating process and relevant design knowledge. The zigzag mapping method and GME tools is used in the process of conceptual design for crane hoisting mechanism in this paper, which verifies effectiveness of the zigzag mapping method and GME tools, and has a certain practical value.