The practical application of silicon based anode for lithium ion batteries is severely limited by the fabrication process of Si nanomaterials, which is complex, costly, and high energy-consuming. Here silicon nanorods have been synthesized from industrial waste fly ash by electrospinning and modified magnesiothermic reaction. The whole process is simple, cost-effective, green and easy to scale-up. While used as an active electrode material in a lithium battery, the obtained silicon nanorods anode exhibits a remarkable lithium storage performance: under the current density of 0.5 C, it could deliver reversible capacity as high as 1136.8 mAh g(-1) after more than 100 cycles. The attractive electrochemical performance of the silicon nanorods is attributed to its 1D nanostructure, porosity and outward nanometer-sized SiOx layer. Meanwhile, the present research makes it possible to accomplish the high-valued application of fly ash and other dust contaminants.