Abstract: An x-ray streaked crystal spectrometer developed by ourselves was first used to measure time-resolved x-ray spectra from line-plasmas of Ge. The time evolutions of the resonance lines of the Ge L-shell spectra were obtained. Also, the electron temperature and its time evolution have been deduced by means of the line-intensity-ratio of the dielectronic capture satellite lines to the resonance lines of the Ge L-shell spectra. The electron temperature in the gain region is approximately 400-760eV, and the period having the relative constant electron temperature is at least 90ps (the variation of the electron temperature is less than 2%).