Surface observation by scanning tunneling microscopy and electron diffraction is capable of providing atomic order information for diamond homoepitaxial films grown by chemical vapor deposition. For diamond {001} homoepitaxial films, a 2×1 structure was mainly observed. The structure suggests growth via dimer row extension. For diamond {111} films, 1×1 periodicity and a local √3×√3 structure were observed. The formation of spiral steps suggests Frank-type growth due to screw dislocation.