The process of three-phase electroslag furnacefoundry casting electroslag remelting was used to produce 316L stainless steel ultra-fine wires with a diameter of 0.018mm. Breakage of the wire often occurs during drawing process due to the existence of inclusions in the steel. In order to improve the cleanliness of 316L steel, the deoxidizer and top slag composition were optimized by industrial trials in this production process. As a result, the total oxygen (T.O.) content decreased from 120 ppm to 57ppm. During the electroslag remelting process, the composition of electroslag and the power supply were optimized. Argon protection was used and electrode was washed by acid solution before refining. Finally, the T.O. in the remelting ingot can be controlled below 20 ppm.