In this study, we explored the players' behavior of gender switching in a MMORPG game. The empirical data is come from the Soul of Magic online game and 65,407 samples were collected for analysis. With regard to the gender of avatars, 37,031 players (56.60%) selected male avatars while 28,376 players (43.40%) selected female avatars. With regard to the gender of players, there were 49,398 males (75.50%) and 16,009 females (24.50%). The result reveal that there were significant differences between the genders of the players who chosen the gender of avatars. One third of male players chose female avatars and one fourth of female players chose male avatars. Among the age layers, 50.17 to 66.12 percent of female avatars are played by male players while 5.85 to 23.60 percent of male avatars are played by female players. According to the result, the gender switching in online games happens more on male players than on female ones.