The disclosure discloses a catalyst capable of simultaneously removing COS and H2S in garbage gasification and a preparation method thereof, and belongs to the technical field of preparation of desulfurization catalysts. The method includes the following steps: pretreating an SBA-15 molecular sieve with a templating agent unremoved, which primarily includes the steps of removing the templating agent and introducing halogen atoms to modify the molecular sieve; then synthesizing an active component solution; and finally introducing active components into channels of the pretreated molecular sieve via surface tension by adopting an impregnation method, performing washing and drying, and performing calcining under an N2 atmosphere, so as to obtain the catalyst. The catalyst prepared according to the present disclosure can load the active components in fixed positions inside and outside the channels, and the components are easy to obtain, thereby having the advantages of low cost and good desulfurization effects.