Professor Emeritus Captain Krisda Arunvongse Na Ayudhya is an architect who has had an important role in the development of modern architecture in Thailand both in the position of faculty teacher and as an architect with a large number of architectural design works. These are works of respected, award-winning architecture, leading to his being recognized as a National Artist in Visual Arts (contemporary architecture) in 2007. This research has as its objective to study his architectural design works to identify the concepts and the patterns during each of the stages of development. The timeframe under study is the period from 1960 to 1989, from the time when he produced his first major architectural work to the time before he shifted away from his architectural career and entered the political arena. Research results show that the development of his architectural design works can be separated into three periods: the early period (1960-1974), the middle period (1975-1985), and the late period (1986-1989). His works during the early period reflected diversity in concepts, forms, patterns and details, considered his period of seeking. During the middle period, his particular patterns became clear, focusing on simplicity so much that it became his design signature. The more advanced materials and technology also affected his design concepts during this period. Finally, in the late period, his design approaches had become more complex, including additional forms. It can be said that his architectural designs started from diversity, developed towards simplicity and then changed to complexity.