Abstract: 2.9%Si-0.77%Al non-oriented silicon steel slab had been produced by the thin slab process with a thickness of 20 mm. After hot rolling,normalizing,cold rolling and annealing,the resulting sheet had been investigated in terms of microstructure,precipitates and magnetic properties. The results show that thin casting slab has a typical transcrystalline grain structure,while the structure of hot rolled strip comprising of fine recrystallized grain at edge and coarse deformed structure in the center. Normalizing process leads to a fully-recrystallized microstructure,and finished sheet is characterized by an equaixed grain microstructure. The precipitates are dominant coarse AlN and (MnS+AlN) composite in size of 0.5~ 2.5 μm. The magnetic property of resulting silicon steel are P₁₅= 2.86 W/kg and B₅₀= 1.70 T.