Hastelloy alloy C-276 strip has been widely used as metallic substrate of YBCO second generation high temperature su-perconductor. The alloy is subject to strict requirements regarding surface polishing quality (roughness Ra in the work). Electrochemical polishing agent shall be controlled effectively and analyzed for variation and failure to guarantee polishing quality. With C-276 strip as object of study, non-contact electrochemical polishing method as well as instruments including SEM, AFM, metallographic microscope and microwave plasma atomic emission spectrometer were used. Functions and process requirements of main components including H3PO4 and H2SO4 in polishing agent were elaborated. Content of H3PO4 and H2SO4, and ionic concentration of Ni, Cr and Mo were measured after unit volume polishing agent passes through electric quantity in certain period (Ah/L). C-276 strip surface roughness will not meet the process requirements Ra <1 nm (5 μm× 5 μm) unless content of phosphoric acid and sulfuric acid fell within 775～1013 g/L and 318～451 g/L, ionic concentration of Ni, Cr, Mo was<7.3 g/L, 2.7 g/L, 3.4 g/L, respectively. Non-contact electrochemical polishing is used to achieve continuous production of the second-generation high-temperature superconducting tapes of kilometric Hastelloy based on effective control of sulfuric acid, phosphoric acid, additives and metal ion concentration in electrochemical polishing agent. The surface roughness Ra is < 1 nm.