Abstract: In order to study the vacuum arc ion source, using a streak camera which could transform the temporal signal to spatial signal, and a spectrograph which could separate an incoming wave into a frequency spectrum, we built a time resolution of plasma optical emission spectra diagnosis experiment platform, and measured the time- and spectral-resolution of this diagnosis system, with a time-resolution of 26 ps, and a spectral-resolution of 0.1 nm. Based on this diagnosis system, the temporal evolution of the plasma and the optical emission spectra were acquired in an only one pulse. At the same time, based on the emission spectra theory of the local thermodynamic equilibrium plasma, we established an emission spectra model, and performed the fitting of the emission spectra of experimental plasma spectra to obtain the temporal evolution of the electron temperature and electron density in plasma. Different from conventional Blotzmann plot and Stark broadening methods needed the isolated line, the fitting model established in this work could deal with the overlapped lines due to broadening. The calculated electron temperature and density were about 1 eV and 3.51024 m-3 respectively.