The structures of ZnTe/GaSb, grown by molecular beam epitaxy under different conditions, were investigated by X-ray triple-axis scattering and crystal truncation rod. The sample annealed under Zn flux from surface cleaning temperature to growth temperature had clear interference fringes in the crystal truncation rod scan profile, while the sample annealed under Te flux shows no interference fringes in the crystal truncation rod. Reciprocal space mapping around the symmetrical diffraction reciprocal point 004 and asymmetrical diffraction point 115 showed that the ZnTe epilayers were fully strained to the substrate. Both two-dimensional reciprocal space mapping and transverse scan along direction showed that the sample annealed under Te flux had strong and broad diffuse scattering in this direction. This was attributed to the Ga2Ｔｅ3 formation at the interface. This interfacial phase would enhance the diffuse scattering, blur the interference fringes and roughen the surface and interface. The epilayer thickness was accurately determined to be (210±1)nm by theoretical calculation of the experimental profiles. The surface roughness of the sample annealed under Zn flux, (2.2±0.2)nm, was smaller that of the sample annealed under Te flux, (3.7±0.3)nm.The lateral correlation lengths of the samples annealed under Zn flux and Te flux are (420±10)nm and (30±5)nm,respectively.