A biomass pyrolysis gasification multifunctional iron-based catalyst and a preparation method thereof are disclosed. The preparation method is characterized by comprising the following steps: (1) carrier pretreatment: placing CaO in a muffle furnace for calcining, then grinding and screening to prepare CaO carrier particles; (2) introduction of a main active component: mixing the CaO carrier particles with a Fe(NO3)3.9H2O solution, stirring and immersing, drying, calcining and grinding; (3) introduction of an auxiliary active component: mixing the sample prepared by the step (2) with a Ce(NO3)3.6H2O solution, stirring, immersing, drying, placing the obtained sample in a muffle furnace for calcining, placing the calcined sample in a dryer to cool to room temperature, grinding, then mixing the obtained powder with a Zr(NO3)4.5H2O solution, stirring, immersing, drying, then placing the sample in a muffle furnace for calcining, then placing the calcined sample in a dryer to cool to room temperature, and then grinding; and (4) shaping of the catalyst: performing shaping on the obtained catalyst, and screening to obtain the catalyst finished product.