This paper investigates the design essence of Chinese classical private gardens, integrating their design elements and fundamental principles. It systematically analyzes the unique characteristics and differences among classical private gardens in the Northern, Jiangnan, and Lingnan regions. The study examines nine classical private gardens from Northern China, Jiangnan, and Lingnan by utilizing the advanced tool of principal component cluster analysis. Based on literature analysis and field research, 273 variables were selected for principal component analysis, from which four components with higher contribution rates were chosen for further study. Subsequently, we employed clustering analysis techniques to compare the differences among the three types of gardens. The results reveal that the first principal component effectively highlights the differences between Jiangnan and Lingnan private gardens. The second principal component serves as the key to defining the types of Northern private gardens and distinguishing them from the other two types, and the third principal component indicates that Lingnan private gardens can be categorized into two distinct types as well.