The characteristics for the evolution of grain orientation and texture of ring shaped blanks of sand- and centrifugal-casting Q235B respectively were investigated by electron backscatter diffraction (EBSD) technique, while the blanks have been subjected to hot compression with a strain rate of 0.1 s^-1 at different temperatures. The results show that the grain size of the blanks after hot compression at 1000℃ becomes smaller in the deformed microstructure, but a few grains maintains as in cast state. The mechanisms of the microstructure evolution may be ascribed to dynamic recovery and large strain geometric dynamic recrystallization. For centrifugal cast ones, the percentage of high-angle boundary in 20°-50° is 22%, but after hot compression at 1100℃ it shows a homogenous microstructure with equiaxed grains because of sufficient recrystallization, while the mis-orientation distribution of grain boundaries still presents a typical characteristic of double-peaks and the proportion of the high-angle boundaries reaches to 60%-75%. The textures of sand casting Q235B are a small amount cube texture {001}<100> and {001}<110> along <001>//ND at 1000℃, while the main textures are Goss texture {110}<001> and r-cube texture {110}<001> at 1100℃. For centrifugal casting ones at 1000℃, {110}<110> and Cu texture {112}<111> distributes along ε orientation; at 1100℃ the types of texture including {001}<110> and {111}<110> transformed from {111}<112> along γ orientation. The orientation density is higher due to the high extent of recrystallization.