The mechanism of CO2 pretreatment significantly improving the activity and anti-coking ability was investigated over the Ni-Co/La2O3-Al2O3 catalyst for carbon dioxide reforming of methane.By a series of catalytic activity measurements,Ni was considered as the main metal that interacted with CO2,and H2 reduction is an indispensible step of the pretreatment route and CO2 cannot be replaced by O2.