The present invention relates to a method for preparing a nickel-based catalyst for steam carbon dioxide reforming (SCR) of natural gas using steam and carbon dioxide, more particularly to a method for preparing a nickel-based catalyst represented by Ni/η-Al2O3, which is prepared by supporting nickel on a spherical η-alumina support having many acid sites at high density by repeating impregnation and drying tens of times.The catalyst prepared according to the present invention exhibits superior catalytic activity when used in steam carbon dioxide reforming reaction (SCR) even under harsh conditions of high temperature and high pressure and hardly exhibits carbon deposition due to superior durability.