Based on the analysis for Problems of the traditional non-aqueous electrolyte extracting inclusions from steel, electrolysis parameters are optimized, then an environment-friendly electrolyte contains γ-butyrolactone is presented, which can completely extract the nano-scale inclusions from the strip proved by experiments. A set of filtering technology of nano-scale inclusions is elaborated. The morphology, size and type of nano-scale inclusions in the strip are detected by SEM and EDS analysis. A kind of detection method of nano-scale inclusions in twin-roll strip casting steel is found.