Twin-roll casting was adopted to fabricate a 2.7-mm-thick material of the non-oriented 6.5 wt% Si electrical steel, which was then hot rolled, warm rolled, and annealed. A detailed study of the microstructural and textural evolutions in the whole processing route was conducted by optical microscopy, X-ray diffraction, and electron backscattered diffraction. Beneficial lambda-fiber texture, strong and Goss textures dominated the annealing texture. Special attention was focused on the origin and evolution of the texture during the annealing process. The results showed that the nucleation sites of the nuclei were not only confined to deformation bands of the deformed grain but also widely distributed in many other deformation heterogeneities of the warm-rolled sheet. The high similarities demonstrated by the nucleation and recrystallization textures, and the gradually intensified recrystallization texture indicated the combined operations of the oriented nucleation and oriented growth mechanisms during the evolution of the recrystallization texture. After recrystallization, some grains which already acquired the advantage in grain size over those clustered grains due to the orientation pinning effect tended to gain further growth during the grain growing stage, resulting in the prevalence of the annealing texture.