The existence of the similar Chinese characters is a special phenomenon which is determined by the rule of Chinese character formation law and the characteristic of configuration for expressive meaning. Traditional understanding located the similar Chinese characters in static similar shape category only according to the standard Chinese characters, it virtually ignored the dynamic adjustment and change of the relationship of handwriting and font in the historical evolution of Chinese character system, it also covered the deep-seated contradictions and the problems of the font between seeking for the simplicity and the difference in the process of Chinese characters system development. Chinese characters as symbols of recording and writing are often static and dynamic use of the organic unity, the similar Chinese characters will be accompanied by the two characteristics of static and dynamic similar shape. The effect between the two levels of static and dynamic interaction made the similar Chinese characters phenomenon presenting similar shape law of absolute and relative, direct and indirect, and so on. The rules and characteristics reflect similar shaped characters not only for seeking common ground, reflecting the character system and the inheritance of structural elements, but also for focusing in difference, reflecting distinction between characters and the different ways of richness, flexibility and subtlety to Chinese characters configuration system. The existence of the similar Chinese characters is essentially the result of the comprehensive function of the internal contradiction of the Chinese character system.

Expression type for mixed-use of Dongba characters can be divided into dominant type and parallel type. Causes for mixed-use includes three points: 1. similar or compatible patterns are the precondition for mixed-use; 2. certain relation exists among semantics of words represented by characters, or characters belong to the same classification in terms of meaning or have correlative meanings; 3. outcome is obtained during self-adjustment transitional stage of internal character of writing system. There are three solutions to solve the problem of similar characters: 1. re-distribution of characters’ functions; 2. integration of characters; 3. reconstruction of expression which is embodied in two aspects, including ideographical and phonetic expression transited from ideographical expression to additional phonetic complement, and transition from ideographical expression to pure phonetic expression.