Mythology is a form of oral and intangible cultural heritage, carrying rich historical and cultural information. The 56 different ethnic groups in China have numerous myths, both diverse in content and handed down in various forms. The present paper will focus on the design, implementation and application of a mythological motif-index database, known as Wang’s Motif-index of China Mythologies Database. There are 33,469 mythological motifs stored in the database, extracted from 12,600 myths from different ethnic groups in China, and divided into ten groups. The paper will give a detailed introduction to the process of motif extraction and database construction. It will also show the interface and search mechanisms provided by the database. With the open-access online, the thematic database is not only applicable to mythology researchers, but also mythology enthusiasts.