The tribological behavior and wear mechanism of a Mo-alloyed layer prepared by a double-glow plasma surface alloying technique were investigated under different loads. The microstructure, the composition distribution and the phase structure of the Mo-alloyed layer were characterized by SEM, EDS and XRD, respectively. The results show that the uniform and compact Mo-alloyed layer with 20 μm thickness is composed of phases Mo, Al3Ti and Al8(Ti3-xMox). The sliding wear experiments were performed under different loads (1.3, 5.3 and 9.3 N) in order to examine the tribological properties of the Mo-alloyed layer. The average friction coefficients and the wear rates of Mo-alloyed layer both show an upward tendency with the increased of loads. Mild abrasion wear and oxidative wear could be detected under 1.3 N load based on the analysis results of 3D surface morphologies, SEM and EDS. The wear mechanism under 5.3 N load is dominated by oxidative wear and abrasion wear. Oxidative wear, abrasion wear and adhesive wear are the main wear mechanism under 9.3 N.