Effects of Co addition on sliding wear properties of multi-component white cast iron were investigated. The microstructures of multi-component white cast iron containing from 0%Co to 10%Co exhibited little difference. However, the hardness increased with an increase of the Co content. Increasing the Co content, wear properties were improved and the iron oxide on worn surface was increased in the low sliding speed range of the steady-state wear region. Hence, Co addition was effective to improve the wear properties of multi-component white cast iron by accelerating the corrosive wear as well as the enhancement effect of hardness.