Focusing on the time evolution of laser induced Cu plasma,the Nd∶YAG pulsed laser was used to excite the Cu sample to generate plasma.The time-resolved spectra of the plasma at the acquisition delay time from 0.5 μs to 20 μs were collected and the overall line spectra were analyzed.When the laser energy was adjusted to 142 mJ,the plasma electron temperature was measured by Boltzmann slope method under thermodynamic equilibrium.Cu I 521.8 nm,which is independent and not affected by adjacent spectral lines,was selected as the characteristic spectrum to measure its half-wave width,and the electron density of the plasma was calculated by Stark broadening method.Experimental results show that with the increase of delay time,internal energy of plasma will suddenly reduced due to continuous expansion into kinetic energy,leading to continuously decline of electron temperature,which reaches the maximum when the delay time is 2 μs.The decline slows down after 13 μs delay time.As the delay time increases,the electron density of the plasma decreases,the collision between the electron and the emitting particles decreases accordingly,resulting in the decline of spectra broadening.