The Cu Kα and Kβ X-ray emission lines of Cu metal and YBa2Cu3O7-δ have been measured by a quasi-double crystal spectrometer. Little chemical shift and line width change have been observed for YBa2Cu3O7-δ. The larger intensity ratio of Cu Kα2/Kα1 in YBa2Cu3O7-δ can be attributed to the existence of the charge transferred state 3d^10L in YBa2Cu3O7-δ.