Both plasma chromizing and carburization following plasma chromizing (duplex treatment) for TiAl-Nb alloy were performed, respectively, and the microstructure, dynamic ultra-microhardness, and elastic modulus of the alloying layer were determined. Using silicon nitride (Si 3 N 4 ) balls as the counterface materials, dry sliding friction tests on the substrate, the chromized layer, and the duplex-treated layer were completed by ballon-disk tribometer at room temperature. The results indicated that the duplex-treated layer was mainly composed of Cr 23 C 6 , Cr 2 Nb, pure chromium, and carbon phases, while the chromized layer consisted of Al 8 Cr 5 and Cr 2 Nb phases. The ultra-microhardness of the duplex-treated layer was higher than that of the chromized layer, whereas the elastic modulus of the duplex-treated layer was lower than that of the chromized layer. The friction coefficient of the duplextreated layer was about three times lower than that of the chromized layer, while the wear rate was one order of magnitude lower than that of the chromized layer.