Cobalt supported on non-porous silicon-based materials with different thermal conductivities for Fischer–Tropsch synthesis is systematically investigated. The product selectivity is independent of the thermal conductivity of the support at low conversion rates. However, at relatively high reaction rates, the product distribution is closely related to the thermal conductivity of the support. This effect is mainly attributed to the thermal management behavior of the catalyst support, which can adjust the thermal micro-environment on and around the cobalt particles. In addition, the sintering degree of cobalt particles on the catalyst surface is strongly dependent on the thermal conductivity of the support.