<p>Planar flow casting stands out for its high efficiency, low-energy use, and short processing cycle, making it a subject of increasing academic interest. The poor fluidity and wettability of high-melting-point, high-viscosity silicon steel melt severely restrict the process window and deteriorate the quality of non-oriented silicon steel ribbons formed <i>via</i> planar flow casting. In addition, the planar flow casting process of solidification and cooling rate is very fast, the size of the melt puddle is very small, so that the small fluctuations in process parameters have a great impact on the quality of the ribbon, only through the parameter adjustment to obtain the ideal performance is a considerable challenge, it is difficult to achieve stable and controllable process of ribbon production. To improve surface quality and magnetic properties, small deformation cold rolling combined with annealing is employed as a crucial post-treatment. Here, Fe−3.0&#xa0;wt pct Si non-oriented silicon steel ultra-thin ribbons were prepared, and the impact of different rolling reductions on their microstructure and magnetic behavior was investigated. The results show that after temper rolling at a 5 pct reduction rate and annealing at 1000&#xa0;°C for 50&#xa0;minutes, the {100} and {110} oriented grains with low storage energy exhibit abnormal growth, and the corresponding volume fractions increase, resulting in the magnetic induction intensity of B₅₀ increase to 1.62&#xa0;T. When the reduction rate exceeds 10 pct, the higher deformation promotes the recrystallization of grains after annealing. The grain size distribution attains a more uniform appearance, and the grain orientation becomes more randomized. The iron loss of P_1.0/400 gradually decreased to 11.65 W/kg with the increase in the reduction rate. It is shown that appropriate post-treatment processes, such as cold rolling and annealing, can effectively improve the comprehensive magnetic properties of silicon steel.</p>