The invention discloses a lanthanum-iron-silicon-based hydride magnetic refrigerant, a preparation method of the lanthanum-iron-silicon-based hydride magnetic refrigerant and a magnetic refrigerator. The chemical formula of the lanthanum-iron-silicon-based hydride magnetic refrigerant is La1-aRa(Fe1-b-cMbSic)13Hd, wherein R represents one or a composition of a plurality types of the following rare earth elements: Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y; a value range of a is 0 to 0.5; M represents one or a composition of a plurality of types of Ti, V, Cr, Mn, Co, Ni, Cu, Zn and Ga; a value range of b is 0.005 to 0.05; a value range of c is 0.069 to 0.162; and a value range of d is 0 to 2. The lanthanum-iron-silicon-based hydride magnetic refrigerant provided by the invention is formed into a block by adopting a hot pressing molding process, introduction of impurity constituents such as an adhesive and the like is avoided, a high thermomagnetic property is kept, the prepared magnetic refrigerant is excellent in mechanical property, the problem of reduction of mechanical properties of pulverization, frangibility and the like of a lanthanum-iron-silicon-based compound after hydrogenation is solved, and performance of the formed magnetic refrigerant can meet the use requirements of the magnetic refrigerator.