Exploring wide multi-disciplinary solution spaces to create conceptual design solutions is a difficult task for human designers due to lack of sufficient multi-disciplinary knowledge. A viable approach would be to develop a computer-aided system to synthesize the wide variety of knowledge for a given design task. However, the existing design synthesis systems are mainly domain-specific, focusing on conceptual design synthesis in a single or few limited disciplines. Therefore, this article introduces the development of a knowledge-based system for multi-disciplinary conceptual design synthesis, including the establishment of a knowledge base for organizing multi-disciplinary principle solutions and a design synthesis algorithm. The implementation of a prototype software is also reported, with the conceptual design of a solar fountain as a demonstrative case. The results of the case study show that the system can automatically and conveniently generate multi-disciplinary conceptual solutions.