Mn1.1Fe0.9P0.8Ge0.2Bx (x=0, 0.02, 0.03, 0.04) compounds were prepared by mechanical milling and subsequent spark plasma sintering (SPS) technique. Their crystal structure was investigated by XRD and the magneticaloric properties were measured by DSC and VSM. Results show that Mn1.1Fe0.9P0.8Ge0.2Bx (x=0, 0.02, 0.03, 0.04) compounds possess a hexagonal Fe2P-type crystal structure. The lattice parameters a and c are changed noticeably with the increase of B, and c/a ratio decreases firstly and then increases. There is a nonlinear relationship between Curie temperature as well as the entropy change and the content of B. The compound achieves the best magneticaloric properties in this system when x=0.02. The Curie temperature increases from 253 K for x=0 to 263 K, and thermal hysteresis decreases from 23 K to 19 K. The maximum value of the magnetic entropy change increases from 28.7 to 32.6 J/kg·K for a field change from 0 to 2 T