Low-defected GaSb and InSb were grown on GaAs by MBE using interfacial misfit dislocations. X-ray reciprocal space mapping can be used to characterize misfit dislocations at the III-Sb/GaAs interface. Uniform interfacial misfit dislocation array were observed by TEM and x-ray RSM. (2 × 8) pre-growth Sb reconstruction promoted the formation of 90° misfit dislocations at the III-Sb/GaAs interface. The electron mobility in GaSb and InSb layers on GaAs can be enhanced through optimizing pre-growth Sb reconstruction.