In this paper, a metric for visual balance computation is presented, and some optimization models for interface composition design are constructed. The interface composition is exhibited through the minimum bounding rectangle of the elements, four basic parameters of the element-x, y coordinates of the starting point, width and height are used for describing the element positioning. Visual moment is used to represent the product of element size and centrifugal distance, and calculate the balance extent of the opposite sides off the centerline. Three optimization models are constructed towards practical design problems such as layout adjustment, attribute selection and scheme optimization. The case study results show that, the quantitative method is effective in user-interface design process, and provides a theoretical basis for designers’ subjective assessment and future computer-aided design.