Abstract: The effects of solution treatment at different time on the microstructure and tensile properties of 7A09aluminum alloy were studied by scanning electron microscope, X-ray diffraction and tensile test. The results show that the tensile strength and elongation of as cast 7A09 aluminum alloy increase firstly and then decrease with the increase of solution time after solution treatment at 475 ℃ for different time and aging treatment at 120℃ for 16 h. The tensile strength and elongation of 7A09 aluminum alloy reach the maximum value of 567 MPa and 8.2% respectively after solution treatment for80 min. There is continuous MgZn₂ phase at the grain boundary of as-cast 7A09 aluminum alloy. With the increase of solution time, more and more MgZn₂ phases dissolve into the matrix. After solution treatment at 475℃ for 80 min, the MgZn₂ phase of7A09 aluminum alloy basically dissolves into the matrix, and the solution effect is best.