The research was completed on quantitative analysis to 92 rare Characters in a new-edition full medical dictionary. It shows there are two reasons which make a lot of rare Character come out from the appendix of the dictionary. One is not handling well the relations (simplified vs. traditional，variants，homophony) among characters. The other is insufficient corporation between computer science and related branch of learning, which makes the rare characters can’t be displayed and inputted. Good foundations of Philology will help distinct on relations among rare Characters. Fontlab software and MoveFileEx Windows API function etc can make characters display and unified update in the network environments.