The invention relates to a composite material of vacuum churning composite granule enhanced aluminum matrix and a preparation technique, which comprises: Si 0-15Wt%, Mg 0-1.5Wt%, Cu 0-2.0Wt%, Mn 0-1.0Wt%, Cr 0-0.4Wt%, Ti 0-0.2Wt%, SiC 0.1-20% (volume proportion). Firstly base alloy is smelted, slag is removed, and refined, churned slowly in vacuum to complete degassing procedure for base melt, the pre-treated enhanced granule is continuously added into the aluminum base melt, mechanical churning to roll the granule into the melt, after the granule is completely rolled in the melt, strong churning and slow churning in reverse direction are conducted so as to disperse the granule evenly in the base; the temperature raises, modifier and refiner are added; the vacuum is dismounted, and placed in static, the floating slag is removed above the melt, and cast. The composition between the granule and the base is realized via vacuum mechanical churning, the joining interface is good, the enhanced granule is evenly dispersed in the base, the prepared composite material has low porosity rate, which is easy to realize industrial mass production.