This paper is concerned with the dry-type tridimensional wound-core transformer. The characteristics and development of the transformer are introduced. An application of dry-type tridimensional opened wound-core transformer demonstrates that it has the advantages of both tridimensional wound core technique and epoxy resin casting. On the basis of all consideration of no-load loss, energy efficient, product size, reliability and flexibility of manufacturing process, it has the value of popularization and application.