This chapter offers an in-depth analysis of the pattern forms, structural composition, and organizational systems found in 73 textile samples from the Atayal, Seediq, and Truku peoples of Taiwan. The chapter identifies 12 primary pattern types: variational, diamond, circular, mortar, zigzag, square, mountain, cross, X-shape, netted stripe, dotted stripe, and line-based patterns. Among these, diamond patterns are the most common (29.6%), followed by stripes (23.9%) and mountain motifs (15%). Each pattern type is analyzed through its internal structure and design elements (e.g., dots, lines, crosses, inverse white spaces), with examples illustrating their diverse and composite forms. Additionally, the study extracts 774 fundamental shape units from the patterns and categorizes them into 205 core design forms, including diamonds, crosses, and mountains. These basic shapes are recurrent across various subgroups, suggesting systemic similarities in pattern construction. The chapter also introduces 11 types of composite stripe structures, including vertical separation, horizontal repetition, X-shaped arrangements, and more. A total of 363 composite stripe groups are identified and classified, demonstrating the geometric and systematic organization underlying Atayal textile aesthetics.