Abstract: The experimental investigation for the diagnosis of plasma produced from the foil-Ge target irradiated by double-laser-pulse is described in this paper. The experiment was performed at “Shen guang” facility.Flat-crystal spectrographs and a time-resolved crystal spectrograph were used to diagnose plasmaparameters. The electron density, the electron temperature and its time revolution are given.The experimental results show that the electron temperature is greatly increased in the experiment driven by double-laser-pulse. The diagnostic results are the basis of selecting the optimum conditions for the gain experiment of the x-ray laser generated from foil-Ge target driven by double-laser pulse.