The purpose of this study is to come up with ways that cooperate between on-line game design and fashion design by analyzing trend color and on-line game character’s costume color in on-line game. As for the research methodology, First, on-line games were selected with reference to www.ranky.com. Second, 2009 SS trend color palettes suggested by Copenhagen International Fashion Fair was used as a criterion of fashion trend. Third, on-line game character's costume colors were analyzed in relation to the degree of reflection of trend and the game character's type. The results are as follows. Each on-line game character costume's colors were made in accordance with typical character types. But we can find a one-to-one correspondence between fashion trend colors and game character costume's colors. That's because both trends and character types are the results of the continuing interactions between human-beings and societies. In comparison with fashion trend colors, game character costume colors are partly raw and inharmonious. Therefore, it is necessary to apply fashion trend color in game character costume design for enhancing competitiveness in the world market.