Steven Holl, a world-renowned architect, is the author of numerous architectural works. Holl is also known for using watercolor sketches with architectural notation to explain his concepts. The use of watercolor sketches to express his concepts, and the fact that he calls his design” Phenomenal architecture”. His watercolor sketches range from planes to isometric projections. The purpose of this research is to clarify the architectural notation methodology by Steven Holl. This study has been conducted by KJ method and extracts descriptions of notation and discusses methodology in his design. Holl has designed to incorporate musical concepts into architectural projects and also to use conceptual sketches of the work as part of the notations in his design theory.