In this work, the poly(butylene terephthalate) (PBT) nanocomposites containing modified nano-Sb2O3 particles were dispersed by two different dispersing techniques, including high speed rotating to disperse (HSR) and high energy ball milling to disperse (HEBM). The dispersion, interfacial interaction and mechanical properties of nanocomposites were investigated. The results showed that the dispersion and compatibility of nanocomposites dispersed by HEBM were better than that of HSR. From the analysis of interfacial interactions between nano-Sb2O3 particles and PBT matrix, the interfacial adhesion (B) and tensile strength of interfacial (sigma(i)) were decreased with the increase of nano-Sb2O3 particles content. The value of parameters B and sigma(i) of HEBM nanocomposites was higher than that of HSR, which indicated that the nanocomposites dispersed by HEBM had stronger interfacial interaction than that of HSR. As a result, the nanocomposites dispersed by HEBM had better mechanical properties than that of HSR.