Trinocular microscopy with a high spatial resolution is a promising technique for studying the surface morphology of materials. The cleavage face of ferroelectric Fe-doped K niobate (KNbO3) crystals was chemically etched by using HNO3. Trinocular microscopy was used to study the surface morphology of the grown ferroelectric KNbO3 single crystals. The grown surface of the crystal with a 60 domain wall revealed the same interaction and orientations. The results indicate that the type of domain walls that occur in ferroelectric crystals depend on the symmetry of both the nonferroelectric and ferroelectric phases of the crystal.