In recent years, due to the popularity of Internet, more and more people use online dictionaries instead of the traditional dictionaries. However, the functions of the existing online Mandarin-Taiwan dialects dictionaries are not complete enough. We developed Mandarin-Taiwan dialects (MinNan and Hakka) online audio dictionaries with speech synthesis technology. The Mandarin-MinNan online dictionary is constructed based on the concept of Web 2.0. And it has 8 major functions. They are phonetic symbols providing, online pronunciation, semantic interpretation, example sentence providing, machine translation, unknown word processing, expanding mechanism providing and test. The purpose of expanding mechanism providing is to increase the number of words in the Mandarin- Taiwan dialects dictionary of our system. Currently the number of words in the bilingual dictionary is still not enough. We hope to solve this problem based on the concept of web 2.0.