Abstract: The spectra of Cu was measured by means of the beam-foil technique. Copper ions of 80 and 110 MeV energy from the HI-13 tandem accelerator in China Institute of Atomic Energy were used, and the wavelength region 11~38 nm was measured. 29 lines were classfied as Mg-like Cu (ⅩⅧ) transitions within the n=3 complex, (i.e.) between the 3s~2, 3s3p, 3p~2, 3s3d and 3p3d configurations.Among these lines, 10 have not been reported previously.