A method for manufacturing a flexible printed circuit board includes having a base layer, and creating a pattern line and at least one conductive pole. The base layer defines at least one communication hole penetrating through the base layer. The pattern line includes two conductive circuit layers formed on opposite surfaces of the base layer. The at least one conductive pole is formed in the at least one communication hole and electrically connects the two conductive circuit layers. A diameter of each conductive pole is less than a diameter of a communication hole.