The invention belongs to the technical field of electric materials and devices, and relates to a method for preparing a flexible polyester nickel-coating electrode. The method particularly comprises the following steps of: performing surface silicification modification on a polyester substrate, and introducing silane coupler molecules, of which the tail ends contain active groups such as sulfhydryl groups, amino groups and acylamino groups on the premise of not damaging surface flatness; performing catalytic activation on the polyester substrate in mixed solution of silver nitrate and glucose so as to make a thin layer of silver catalyst coated on the polyester substrate undergoing silicification, wherein the silver catalyst layer and the substrate are connected by chemical bonds; and finally performing chemical nickel-plating in the presence of silver catalyst. The polyester nickel-coating electrode prepared by the method has the advantages of strong adhesion between the nickel coating layer and the substrate, stripping strength of more than 40N/cm, high smoothness, root-mean-square roughness(Rrms) of less than 15nm (the area is 5mu m*5mu m), high electric conductivity, and lower resistivity (5.3 mu omega.cm) compared with that of pure nickel. The flexible polyester nickel-coating electrode can be widely applied to solar batteries, membrane ion secondary batteries, flexible organic electric devices, and the like.