The invention discloses a catalyst applicable to synthesis-gas preparation by catalytic reforming of shale gas and carbon dioxide and a preparation method thereof. The catalyst is prepared from the following components in percent by mass: 5%-10% of main active component (nickle), 3%-5% of secondary active component (cerium), 20%-30% of anti-carbon-deposition magnesium oxide and carrier, wherein the mass ratio of the nickle to the cerium is (1-3):1, and the carrier is one or more of titanium oxide, aluminium oxide or silicon oxide. The catalyst disclosed by the invention has the advantages of low reaction temperature, high catalytic activity, good anti-carbon-deposition and good stability, and is applicable to industrial application of fixed beds or fluidized beds. The catalyst has the beneficial effects that in the catalytic reforming application of the shale gas and CO2, the pressure is normal pressure, the reaction temperature is 500-900 DEG C, not only can effective and clean utilization of shale-gas resources be realized, but also two types of greenhouse gases can be treated simultaneously, the greenhouse effect is relieved, and the product has proper H2/CO ratio and can be directly applicable to other fields of Fischer-Tropsch synthesis and the like, so that the industrial application prospect is wide.