Ordered-mesoporous materials have a relatively high surface area and a uniform meso-pore structure and can be used for gas sensors or heterogeneous catalysis. However, the pristine mesoporous materials in Fischer-Tropsch synthesis showed a severe structural instability. In this study, the mesoporous-Co₃O₄ was synthesized using hard template of KIT-6, and structural stability was improved by using Al₂O₃, an irreducible metal oxide as a pillar. In addition, its long-term stability can be ensured by injecting n-octane in real time. When a proper amount of alumina (5~10%) was impregnated, the catalyst stability was better than that of pristine mesoporous-Co₃O₄. However, the deposition of hydrocarbon (wax) on those catalysts was significant due to a higher activity. The deposited waxy hydrocarbons was effectively removed by the saturated hydrocarbons (n-octane) injected during FTS reaction, and the catalytic activity was regenerated with time on stream.