The purpose of this article is to study and examine the forms and meanings of the Chinese character ”dan”(蛋). Its form has established around the Tang Dynasty and, according to the popular forms used then, is an erroneous transformation from the character ”dan”(蜑). And for the meaning, this article will, based on previous studies, provide further research and analysis on the forming and development of ”dan”(蛋), meaning eggs of bird. Relevant corpus will be compared and generalized to give a general description of how the character ”dan”(蛋), eggs of bird, had developed. ”Dan”(蛋) begins to carry the meaning ”eggs of bird” around the Northern Song Dynasty, through the Yuan Dynasty and Ming Dynasty, and the meaning finally takes root in Qing Dynasty.