Ethnic garment construction was investigated from the perspective of geometry. Basic characteristics of ethnic garment construction of different regions and nationalities were analyzed and summarized. Features of silk and the decisive role playing in the forming of geometrical garment structure of Chinese ethnic costumes which have great impact on the style features of oriental ethnic costumes were mainly discussed. The aesthetic features and philosophic ideas silk endows Chinese traditional garment were also discussed. By exploring the wisdom and skills of ethnic garment construction design, the geometric characteristics of ethnic garment construction, the basic rule of changes in ethnic garment construction and the essence of the construction structure variation were revealed. Inspiration from the techniques of ethnic garment construction design will be valuable for us to explore innovative ideas for today’s fashion design.