The invention provides a method for preparing a fine line circuit board by filling grooves by means of selective plating. The method includes the following steps of: 1) forming a flexible material layer on a surface of the substrate and forming a plurality of groove structures; 2) forming a seed layer on surfaces of various groove structures and a surface of the flexible material layer; 3) forming conductive metal by adoption of selective plating, wherein the growth rate of the conductive metal in various groove structures is greater than that of the surface of the flexible material; and 4) removing the conductive metal on the surface of the flexible material, and remaining the conductive metal with a certain thickness in various groove structures. According to the method, the steps of imprinting, sputtering, electroplating and corrosion can adopt a roll-to-roll process; the formed circuit is wrapped in UV curing glue, is high in reliability, and is not easy to damage; and the cost of an electroplating process is low, which can provide a solid and reliable enabling process for that the fine line circuit board can be prepared in a large scale by adoption of an imprinting method in the future, relevant process chains can be driven, and the huge social value can be formed.