Through pin-on-disc friction and wear experiments, the tribological properties and wear mechanisms of a 20 vol.% Mg2Sn/Mg composite fabricated by powder metallurgy were systematically investigated. The experimental results show that with the quenched 45 steel as the counterface material and under a sliding speed of 0.126 m/s, both the coefficient of friction (COF) and wear rate (Wr) of the composite gradually decreased with increasing load in the range of 10 to 80 N. At a load of 80 N, the COF and Wr of the composite reached 0.25 and 6 × 10-10 mm3/Nm, respectively. The excellent tribological performance is primarily attributed to the formation of a hard nanocrystalline friction-affected layer during sliding, and to the effective load support and stress dispersion capabilities provided by the high volume fraction of Mg2Sn particles.