The selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol was performed on Cu–SiO₂ catalysts prepared by a precipitation–gel method with different Cu contents and pretreatment temperatures. As a result of the uniform distribution of Cu particles on these catalysts, their activities and combined selectivities to ethylene glycol, propylene glycol, and glycerol increased consistently with the increasing Cu particle size and reached maximum values at around 11 nm in the range of 4.0–38.0 nm. After the reaction conditions and catalyst pretreatment temperatures were optimized, a high combined yield to the target glycols of up to 70.4% was achieved on 90%Cu–SiO₂ catalyst at ≈100% xylitol conversion. The 90%Cu–SiO₂ catalyst can be recycled in successive runs without a significant loss of activity and selectivity by recalcination and reduction treatment after each run.