Fashion industry is faced with issues of raising the competitiveness of established designers recently. As well as the change of business system, the specialization of professionals in design team increases the needs of in-service training of fashion designers. But, the education programs of enterprise are generally focused on adaptability to the organization and harmony among men as an introduction level. Furthermore, there are few professional institutions that give an education to the working-level designers. Thus, this study aimed at development of specialized in-service training program that could educate established designers for more integrated thought to cope with rapid changes in the fashion field. Firstly, the theoretical study on the in-service training and changes of fashion environment had been studied through literature review. Then, the current state of in-service training of fashion enterprises and the courses for established designers in fashion institutions were analysed. Finally, a comprehensive framework of in-service training program for fashion designers has been established as a result of this study. The program was designed in accordance with the previous research which reached 4 different educational needs for in-service training: brand planning and management, understanding production, understanding practical fabrics & colors, computer program. The study went further to apply the program to each design group divided by career: new designer, junior designer, senior designer, design leader. This study also suggested evaluation process to confirm the effects.