As a non-destructive and subsurface detecting technique, the scanning electron acoustic microscopy (SEAM) method has been applied to study the ferrodomain structures in ferroelectric BaTiO3 single crystal and ceramics. The domain arrangements and the orientations of domain walls at different geometry structures in the BaTiO3 single crystal, and the relationships of domain structures with surface grains in the BaTiO3 ceramics, have been discussed by analysing the experimental results obtained at different operation conditions. The distributions of electron acoustic signals with modulation frequencies up to 1 MHz have been obtained. The relationship of the electron acoustic signal with incident electron energy has also been studied. Although the thermal wave coupling mechanism makes a certain contribution to the acoustic signal generations, the image contrast of ferrodomains is dominated by differences in the electrical properties of ferroelectric materials.