Alumina supported Ru catalysts with different metal content were prepared via the adsorption precipitation Method using RuCl3 as the precursor and characterized by temperature-programmed reduction and XRD techniques. These catalysts were evaluated using selective. hydrogenation of dimethyl maleate as a probe reaction and results revealed that :superior catalytic performances were obtained at mild hydrogenation conditions (1.0 MPa and 70 degrees C). From the temperature programmed reduction results, several states of ruthenium,on the support can be discerned and the proportion of ruthenium species reducible at the low temperature (95 +/- 5 degrees C) decreased With increasing ruthenium loading and was largely influenced by pretreatment conditions It has been confirmed that ruthenium species that can be reduced at low temperature may Mainly contributed to the catalytic activity. On the basis of the above findings, effective turnover number was introduced to better evaluate the catalytic performance.