The invention relates to a method for welding silicon cores, which comprises the following steps: finishing welding faces, placing silicon cores, starting a silicon core furnace and a high frequency induction heating coil, thermally melting the silicon cores, keeping temperature and reducing the temperature; and recycling or laying aside for later use the integrally welded silicon cores. In the method for welding the silicon core, through the welding of the silicon cores having basically the same diameter and components, waste is recycled and part of crushing, zone-melting and silicon drawingcost is saved. The method is also applicable to the production of polysilicon. The silicon cores are softened at 800 DEG C to achieve ductility and then made into required lengths and shapes by the welding method of the invention, and a seamless loop is formed by a silicon core.