Abstract: The three major laws of character development are that expression, distinction, and simplicity are of great importance to the Chinese phonetic characters. The law of character development is one of the reasons for the emergence of borrowed words. At the same time, the law also promotes the development of writing under the guise of words and the phonogram conversion, forming a sound symbol as the core, and is replaced by shape symbols of "simultaneous interchangeable" text phenomenon. Under the influence of the law of character development, the internal structure of the word is constantly adjusted, and the relation becomes clearer and clearer from the original complex and varied relations of the guise. In addition, the development of writing law is throughout the entire loan character developing process, which optimizes the loan character function and makes Chinese characters a more perfect record of Chinese words and the Chinese characters relations gradually clear.