Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) was applied to study the geometrical structure of epitaxially grown MgO layers on a TiC(001). The hetero-epitaxial MgO layer was able to be deposited by thermal evaporation of magnesium onto the TiC(001) surface and subsequent exposure of oxygen at room temperature. A slight heating of the substrate at around $300^{circ}C$ was necessary to overcome a thermal barrier for the ordering. The well-ordered MgO structure was confirmed with the 1$ imes$1 LEED pattern. TOF-ICISS was useful in studying interface structure between oxide and substrate. The results revealed that the MgO layer is formed at the on-top sites of the TiC(001) substrate and the lateral lattice constant of MgO layer is the same as that of the TiC substrate. The MgO was deposited within two layers on the most parts of the surface.