Abstract: The Al-5Ti-1B grain refiner was prepared by continuous casting and extrusion process with electromagnetic stirring. The effect of electromagnetic stirring on microstructure and grain refining efficiency of Al-5Ti-1B grain refiner were investigated. Results show that the agglomerating and precipitating of TiB₂ particles in Al-5Ti-1B melt can be prevented by electromagnetic stirring. The distribution of TiB₂ particles in α-Al and grain refining efficiency of Al-5Ti-1B grain refiner can be improved by electromagnetic stirring. The content of Ti and B are 5.08% and 1.02%. The average size of TiB2 particles uniformly distributed in the α-Al is 0.74 μm. The average size of TiAl3 phase with square shape is 15.7 μm. The grain average size of pure aluminum with adding 0.2% Al-5Ti-1B grain refiner and holding 2 min are refined from 2800 μm to 68 μm. When the holding time is prolonged to 120 min, the grains coarsening are not occurring.