By using of Nd:YAG pulse laser, spectral lines of copper are experimentally studied in air atmosphere. The plasma characteristic spectral line of copper is obtained by 119.1, 154.6, 201.7 and 256.2 mJ·Pulse-1 energy. CuI 510.5 nm and 521.8 nm are selected as the research object. The relationship between spectral line intensity and laser energy is analyzed and it is found that the broadening line is Lorenz and Gauss respectively. The results show that different bands correspond to different spectral broadening mechanism for Cu plasma emission spectrum and with the increasement of laser energy, the spectral line intensity is increased gradually, and the full width at half maximum (FWHM) of the spectral lines also increased.