With the aid of scanning electron microscopy (SEM),energy-dispersive spectroscopy (EDS),X-ray diffraction (XRD),differential scanning calorimetry (DSC)analysis and electron backscatter diffraction (EBSD),the microstructure of the alloy in as-extruded state and various solution-treated states was investigated.The results indicate that second phase of the as-extruded 7136 aluminum alloy mainly consists of Mg(Zn,Cu,Al)2 and Fe-rich phases.The Mg(Zn,Cu,Al)2 phase directly dissolves into the matrix during solution treatment with various solution temperatures.After solution treated at 475 ℃ for 1 h,Mg(Zn,Cu,Al)2 phases are dissolved into the matrix,while Fe-rich phases still exist.Fe-rich phases could not dissolve into the matrix by prolonging solution time.The mechanical property test and EBSD observation show that two-stage solution treatment makes no significant improvement in mechanical properties and recrystallization of the alloy.The optimized solution treatment parameter is chosen as 475 ℃/1 h.