The influences of boron addition on the phase formation, Curie temperature and magnetic entropy change of the NaZn 13-type La(Fe 0.9Si 0.1) 13 compound have been investigated. Eight boron containing La(Fe 0.9Si 0.1) 13B x samples were prepared with x=0, 0.03, 0.06, 0.1, 0.2, 0.3, 0.5 and 0.6, respectively. Experimental results show that a small amount of B addition in La(Fe 0.9Si 0.1) 13 forms the solid solution NaZn 13-type structure phase by substituting B for Si or doping B into interstitial position of the lattice, preserves its giant magnetocaloric effects due to their first-order structural/magnetic transition, as well as increase its Curie temperature T c slightly. The maximum magnetic entropy changes in the magnetic field change of 0–1.6 T are around 20 J kg –1 K –1 for the samples with Boron addition less than 0.3, while improving the Curie temperatures by 2 K.