The effects of different amount of Al-5Ti-1B grain refiner on microstructure and secondary solidification of 7A04 aluminum alloy semisolid slurry were investigated. The results show that the primary α-Al particles of 7A04 aluminum alloy semisolid slurry could become fine and globular by addition of 0.1% Al-5Ti-1B grain refiner, the microstructure with average particle diameter 71μm and shape factor 0.49 of primary α-Al particles at 630℃could be obtained.The amount of Al-5Ti-1B grain refiner was higher than 0.1% and the effect of refining was not obvious. As the temperature increased, microstructure of semisolid slurry of 7A04 aluminum alloy got fine but the shape factor deteriorated. The microstructure of semisolid solidification with fine and globular α₂ particles could be achieved by addition of Al-5Ti-1B grain refiner, but there was little change with average particle diameter and shape factor of α₃ particles.