The invention discloses an open-type three-dimensional wound core and a method of manufacturing a transformer by using the same. The transformer comprises a coil and one or more core single frame, wherein each core single frame is formed by winding silicon steel sheets and comprises a core column for winding of the coil; an upper yoke part is formed at the top end of each core column and is provided with an interface; and the interface is arranged on the upper yoke part of each core single frame. The cut upper yoke part of each core single frame can be straightened along the corresponding core column through the interface and is conveniently sleeved with the wound coil, and the core single frame and the coil can be simultaneously wound, so that the production efficiency is improved; too many professional devices do not need to be input in the manufacturing process; the investment cost is reduced; and development and application of a three-dimensional wound core technology are effectively promoted.