Stress-induced martensitic transformation plastic zones of ceria-stabilized tetragonal zirconia polycrystalline ceramics, under some typical loading conditions, were studied by Moire interferometry. The full-field fringe patterns, including u-fields and v-fields, were acquired. According to these patterns, the transformation zone shape and transformation plasticity distributions of the specimens were obtained. The experimental results show that the stress-induced transformation at room temperature is concentrated in some narrow bands and the transformation plasticity is not uniform within the transformation zone. Experiments also reveal that the transformation zone with a characteristic elongated shape ahead of the notch, in a single-edge notch bending specimen, is obviously different from that resulting from some constitutive relation of transformation. This work provides a significant experimental foundation for establishing the theoretical models of transformation toughening.