The invention provides a method for preparing a NiW alloy composite baseband billet used for coating conductors by the smelting process and belongs to the technical field of billets. The method comprises the following steps: firstly preparing a NiW alloy with a high W content, which is used as an inner layer, putting the NiW alloy in a die; injecting a smelted NiW alloy with a low W content on the periphery of the NiW alloy with a high W content in an Ar/H2 shielding atmosphere to form a smelting composite cast which uses the NiW alloy with a low W content as the outer layer and the NiW alloy with a high W content as the inner layer; subjecting the smelted composite cast to homogenizing theramal treatment; performing high-temperature hot-forging and hot-rolling to obtain a smelting NiW alloy composite billet. According to the composite billet provided by the invention, the inner and the outer layers are bonded closely without the risk of cracking. The NiW alloy composite billet prepared by the smelting process is the basis of preparing a composite long band and facilitates the implementation of the industrial production of composite long bands.