The purpose of this study is to reestablish the innovative and experimental designs of Rei Kawakubo by considering and analyzing the flow on the avant-garde nature of her design collection from 1981 to 2017. Design trends such as the art trend, silhouette, color, and expressive technique showcased in Rei Kawakubo’s collection from 1981 spring/summer to 2017 spring/summer were examined through precedent studies, books, internet materials, and the avant-garde expressive nature of her designs appearing in modern fashion. Additionally, this study considers the definition of avant- garde and analyzes the expressive nature of Rei Kawakubo’s 137 works from the Comme des Garcons collection, exhibited in New York’s Metropolitan Museum of Art. As a result of this examination, the avant-garde expressive nature seen in modern fashion was classified into the following themes: historicity, de-structure, exaggeration, intermixture, and surrealism. As a result of reclassifying these characteristics according to historical flow, the historicty, intermixture, and de-structure appeared in the 1980s, while intermixture, exaggeration, and de-structure appeared in the 1990s. More recently, historicity, intermixture, and de-structure appeared in the 2000s, and intermixture, de-structure, exaggeration, and surrealism appeared in the 2010s. The present study is significant in providing theoretical material for the more innovative and various design development in diverse domains while helping to define and understand the avant-garde expression through Rei Kawakubo’s collection.