As the output of the stainless steel is increasing year by year, the waste acid produced by pickling the stainless steel is also increasing year by year. The waste sulfuric acid solution discharged by pickling the stainless steel contains a large amount of free acid. According to the acid recycling process developed by our research group, the free acid concentration in the waste acid can increase to obtain the regenerated sulfuric acid while quite effectively recovering these valuable metal ions in the waste acid. In this work, the technology of recovering sulfuric acid from the stainless steel pickling waste solution by the solvent extraction was studied, aiming at the problems of high concentration of regenerated sulfuric acid in the stainless steel pickling waste solution, high consumption of neutralization treatment reagent, large amount of waste residue, and so on. It was found that the organic system of 40% (volume fraction, the same below) tris-2-ethylhexylamine (TEHA)+50% isomeric tridecyl alcohol+10% Exxsol D110 was the optimal composition. The extraction rate of sulfuric acid increased with the increased concentration of TEHA. With the temperature increasing of the extraction, the extraction rate of sulfuric acid decreased, indicating that the extraction reaction was exothermic reaction and the enthalpy (ΔH) of the extraction reaction was calculated as ?7.5708 kJ/mol. McCabe-Thiele diagrams were drawn according to the distribution curves of the extraction and the stripping. Under the condition of 30℃ and A/O=1:2, the extraction rate of sulfuric acid could reach 79.8% by 3 stages (theoretical). Using the deionized water as the stripping agent, the stripping rate of sulfuric acid could reach 85.5% after 3 (theoretical) stages at 30℃ and A/O=1:1. The kinetics of the extraction and stripping was very fast and the phase separation was rapid at the same time, which can perfectly meet the requirements of industrial continuous production.