The invention discloses a preparation method of La (Fe, Si) 13Hx hydride magnetic refrigeration materials. The preparation method includes the steps: selecting a solid hydride, and respectively performing ball milling, crushing and refining for the solid hydride and La (Fe, Si) 13Hx alloys; uniformly mixing two kinds of refined powder, and performing pressing and forming for the mixed powder to obtain block-shaped materials; performing vacuum sealing tube for the formed block-shaped materials, performing heat treatment for the block-shaped materials in a heating furnace to obtain the La (Fe, Si) 13Hx hydride magnetic refrigeration materials. The decomposition temperature of the solid hydride is lower than that of the La (Fe, Si) 13Hx alloys, and the heat treatment temperature is in between the decomposition temperature of the solid hydride and the decomposition temperature of the La (Fe, Si) 13Hx alloys. According to the method, solid seepage hydrogen is achieved, the Curie temperature of La (Fe, Si) 13 can be successfully improved, giant magnetocaloric effects can be kept, and solid seepage hydrogen is simple to operate and low in potential safety hazard as compared with gas seepage hydrogen.