Preparation of semi-solid microstructure with less liquid content of 7A09 aluminum alloy industrial extrusion billets is studied in this paper. In the treatment, melting-stirring and predeformation of the alloy billets are not required. The influences of different heating temperatures and insulation time on the microstructure evolution are studied and the obtained microstructure is observed and analyzed by optical microscopy. The results indicate that a fine microstructure can be obtained with the proposed process and the processing parameters can be controlled over a wide range. The liquid content can be controlled within a certain range.