La_0.8Ce_0.2Fe_11.7-xMn_xSi_1.3 master alloys were prepared by medium frequency induction furnace, then annealed, saturatedly hydrogenated, and finally crushed into powders. The multiple components of La_0.8Ce_0.2Fe_11.7-xMn_xSi_1.3H_1.8 (x=0.23, 0.26, 0.29, 0.32, wt%) powders with the Curie temperature (T_C) interval of 5 K were mix-bonded by epoxy resin to extend the full width at half maximum of magnetic entropy of alloy. The magnetic properties of the mix-bonded specimens were measured by VersaLab and adiabatic temperature change direct test device. The maximal magnetic entropy change of the mix-bonded specimens is decreased, whereas the full width at half maximum of magnetic entropy and the relative cooling power are increased, compared with those of the single-component-bonded specimens. The maximal relative cooling power is 139.2 J/kg for the four-component-bonded specimen.