The invention relates to a preparation method of a catalyst used for preparing a liquid fuel by oil and fat hydrogenation. The method comprises the following specific preparation steps: firstly, mixing a calcined ZSM-22 molecular sieve and an amorphous oxide precursor, performing strip extrusion, performing molding, and performing calcination to prepare a carrier precursor; filling pore channels of the carrier precursor with monomer molecules of a polymer, and performing heating treatment to obtain a carrier with partially-covered molecular sieve acidic sites and partially-blocked molecular sieve pore channels; and supporting a metal active component on the carrier, performing drying, and performing reduction to obtain the target catalyst. Compared with a catalyst prepared in the prior art, the catalyst prepared by adopting the method provided by the invention has the higher isoparaffin selectivity and yield in the process of preparing the liquid fuel by oil and fat hydrogenation.