Abstract: The semi-solid forming technology can significantly improve the performance of 7075 aluminum alloy. 7075 aluminum alloy slurry was prepared by using rotating heat equilibrium method.The effect of casting temperature and rotation time on the semi-solid structure of 7075 aluminum alloy was studied. The results show that when the pouring temperature is reduced from 665℃to 635℃, the average grain size of the slurry decreases from 118 μm to 72.4 μm, and the shape factor increases from 0.52 to 0.72.When the rotation time is extended from 60 s to 120 s, the grain size increases from 67 μm to 95 μm, and the shape factor decreases from 0.67 to 0.56.