A method and a system are provided for replacing the theme of a mobile terminal on the basis of a user's clothes color, including: setting an RGB value interval of clothes through analyzing the RGB values of all pixels of the clothes location in the obtained image and calculating the clothes RGB average, analyzing the RGB values of all pixels of every theme on a mobile terminal, calculating the theme RGB value average; when the theme RGB average is within the clothes RGB average interval, and replacing the theme of the mobile terminal by the theme corresponding to the theme RGB average. Thus, the mobile terminal becomes more interesting.