Nanomaterials refer to new materials that are constructed from a unit structure of one to one hundred nanometers according to certain organizational rules. The purpose of this paper is to apply nanomaterials in the study of visual effects of ethnic dress pattern design. This paper first gives a brief overview of ethnic costumes, including the status quo, development, characteristics of ethnic costumes, and also studies the pattern design and visual effects of ethnic costumes, as well as the image shaping of pattern design. Then, the content of nanomaterials is elaborated. Finally, nanomaterials are applied in the design of ethnic costumes, and they are compared with traditional ethnic costumes, and the functionalities of the costumes and the visual effects of pattern design are observed, respectively. The results show that the overall average score of the visual effect test of ethnic dress pattern design using nanomaterials reaches 8.54 points, which verifies its effectiveness.