Experiments were performed to determine the electron temperatures of Mg/Al disk target and gold disk target mixed with tracing Mg/Al materials irradiated by laser beams at a wavelength of 0.35μm from the “Xing Guang Ⅱ”high-power laser facility.X-ray spectra from the targets were measured by a crystal spectrometer.The technique of multi-configuration Dirac-Fock was used to calculate relevant atomic parameters.Variations of relative intensity of isoelectronic lines from the two tracing ions in laser-produced plasmas with the electron temperature were derived according to local-thermodynamic-equilibrium model.Based on the above-mentioned experiment the electron temperatures of the plasmas generated by focusing laser pulse on the targets were determined via isoelectronic line ratios.