Microstructure and magnetization behaviors of MnBi/Fe₃B/Nd₂Fe₁₄B nanocomposite alloy have been investigated. It was found that the coercivity increased firstly and then decreased, and saturation magnetization decreased with the additon of MnBi alloy. The addition of 40 wt.% MnBi powder enhanced the coercivity from 192.8 kA/m to 311.2 kA/m. The δM and D(H)-H plots suggested the occurrence of a stronger exchange-coupling occurring between the hard and soft magnetic phase for this sample. The dependence of coercivity with temperature was discussed in 40 wt.% Mn₅₅Bi₄₅/ 60 wt.% Nd4.5Fe76.5Nb0.5B18.5 alloy powder, and a positive temperature coefficient was founded from 298 K to 350 K.