|This study develops a Hanbok Jeogori pattern for middle-aged women with a 3D virtual-twin and virtual-garment simulation system. The including criteria for subjects in this study was a focus on women in their 50s, and a total of 345 females satisfying them were enrolled for 3D virtual model. Comparative Jeogori pattern, Baik & Choi`s(2004) pattern, was selected for the development of Jeogori pattern. The results were: first, a new Jeogori pattern considerate of middle-aged women was developed, The basic numerical formula were, Front and back bust girth B/4+1.5, armhole depth B/4, sleeve width B/4, goedae width B/10-1.5 and git width 5.5. Second, according to the results of the new Jeogori patterns appearance evaluation, the new Jeogori pattern scored higher than the existing pattern in silhouette and ease amount, this confirmed that the new Jeogori pattern is appropriate for middle-aged women. Virtual models of production through data from 3D body scan, pattern draft, and virtual garment digital program were applied to a prototypic design method to enhance the fitness of ready-made Hanbok garments. This study serves as important basic data for ensuing studies that may utilize 3D Virtual Garment Simulation System with 2D patterns and for the future 3D Pattern Production Program development of Hanbok patterns.