This study focuses on large-size male body types and explores personalized pattern modification methods for bespoke suits. Through a detailed classification and analysis of obesity-related body characteristics, the research finds that large-size men commonly exhibit features such as a waist circumference exceeding the chest circumference, altered shoulder angles, widened back width, and variations in arm proportions. These traits often result in issues with standard suit patterns, including gaping or bulging at the placket, flaring of the hem, shoulder wrinkling, and mismatched sleeve lengths. To address these problems, this paper proposes a series of modification methods, including lengthening the front waist section, adjusting shoulder slopes, correcting the armhole and sleeve cap, and adding abdominal darts, followed by optimization based on fitting feedback. The results demonstrate that the modified garments show significant improvements in fit, comfort, and aesthetic appearance, while also enhancing the confidence and social recognition of large-size men. This study not only provides practical guidance for bespoke suits tailored to large-size body types but also lays a theoretical foundation for future applications of digital technology in achieving precise modifications.