This study developed a user focused interface to improve a temperature regulation smart wear system controlled by a textile switch embedded on the outer surface. Designers need to investigate problems between design and consumers to enhance usability. Companies usually launch a final product where problems are resolved by repeated usability evaluation from the initial stage of product development. A textile switch was made all fabric for natural wear ability and designed for easy control and hands-free operation. Usability evaluation for textile switch design was conducted after reading manual without functioning. The survey selected five possibilities (metaphor, consistency, efficiency, flexibility, and aesthetic) from 10 heuristic evaluation assessment criteria of Nielsen(Feedback, metaphor, control, consistency, error prevention, efficiency, flexibility, aesthetic, recover form error, and help) to evaluate with a 5-point Likert-type rating scale restricted by 17 questions that collected specific opinions about user satisfaction. We randomly selected 20 general users to conduct the survey. A textile switch was made all fabric for natural wear ability and designed for easy control and hands-free operation. Usability evaluation for textile switch design was conducted after reading manual without functioning. The survey selected five possibilities (metaphor, consistency, efficiency, flexibility, and aesthetic) from 10 heuristic evaluation assessment criteria of Nielsen(Feedback, metaphor, control, consistency, error prevention, efficiency, flexibility, aesthetic, recover form error, and help) to evaluate with a 5-point Likert-type rating scale restricted by 17 questions that collected specific opinions about user satisfaction. We randomly selected 20 general users to conduct the survey. Textile switch is suitable for the interface of temperature regulation smart wear systems in terms of usability, because it synthetically presented high user satisfaction standards. We modify the final prototype based on usability problems selected through subjective evaluation.