Abstract: In this study, in-situ generating MoB ceramic reinforced Cu-Sn-Al alloy composites were successfully prepared by sintering the raw materials of Cu, Sn and MoAlB powders via fast hot-press sintering route. The influence of the content of MoAlB ceramic reinforcement on the microstructure and tribological properties of the as-prepared composites were studied, and the friction and wear mechanisms of the composites were discussed as well. It was established that when the MoAlB ceramic particles were doped in the Cu-5Sn alloy matrix, Al element in the layered MoAlB ceramic could be diffused out of MoAlB matrix and diffused into the Cu-5Sn alloy matrix during the sintering process, resulting in the formation of in-situ MoB ceramic particles reinforced Cu-Sn-Al alloy matrix composites. Because of the dispersion strengthening effect of in-situ forming MoB particles, the as-prepared Cu matrix composites could exhibit enhanced mechanical properties. It was confirmed that the Vickers hardness, compressive strength and flexural strength of as-prepared composites were greatly improved in comparison with as-prepared Cu-5Sn alloy. When the mass fraction of MoAlB was as high as 30%, the hardness value of the composite was about 321.2 HV_0.1, which was approximately five times higher than that of as-prepared Cu-5Sn alloy. As the mass fraction of MoAlB was as high as 10%, the as-prepared Cu matrix composite had the highest compressive strength and flexural strength, where the compressive strength and flexural strength were 1 156.5 MPa and 822 MPa, respectively. When the mass fraction of MoAlB further increased, the compressive strength and flexural strength of as-prepared gradually decreased. Furthermore, the friction coefficient and wear rate of as prepared composites gradually came down with the mass fraction of MoAlB increasing up to 30%. For as-prepared Cu-5Sn alloy, the friction coefficient and wear rate were 0.67 and 3.60×10⁻⁴ mm³/(N·m), respectively. The main wear mechanisms were two-body abrasive and adhesive wear. When the mass fraction of MoAlB ceramic increased from 10% to 20%, the friction coefficient and wear rate of as-prepared Cu matrix composites came down from 0.48 and 1.75×10⁻⁴ mm³/(N·m) to 0.46 and 1.30×10⁻⁴ mm³/(N·m), respectively. Due to the pining effect of in-situ generated MoB particles, the plastic deformation of the matrix material in the friction process can be inhibited, which could obviously reduce the two-body abrasive and adhesive wear. Besides, the addition of MoAlB also could promote the tribo-oxidation reaction during the sliding process, in which the tribo-oxidation products mainly consisted of the oxides of Mo and B. The tribo-oxidation products generated on the worn surface during the sliding can reduce the adhesive wear and two-body abrasive wear, which can provide excellent lubricating effect to reduce friction and wear during the sliding process. Hence, as the mass fraction of MoAlB ceramic climbed up to 30%, the as-prepared Cu matrix composite exhibited better lubricating effect, where the friction coefficient and wear rate were as low as 0.33 and 5.4 × 10⁻⁵ mm³/(N·m), respectively.