This invention has disclosed a kind of producing method for DL-mandelic acid; comprising the steps of: cyanidation, mix benzaldehyde with acidity or alkaline catalyst, supplement water, add cyaniding hydrogen air or hydrocyanic acid solution, react to mandelonitrile; -hydrolysis, put mineral acid into the solution and hydrolyze, form hydrolysis solution contained DL-mandelic acid and mineral acid ammonium salts after hydrolysis entirety; -crystal, supplement water and cycle mother liquor into hydrolysis solution, crystallisate by cooling, centrifugal separate to find DL-mandelic acid coarse product and mother liquor contains DL-mandelic acid and mineral acid ammonium salts; mother liquor handling, adding inorganic basic substance, crystallisate by cooling after ordinary pressure or reduction concentrating, centrifugally get rid of mineral acid ammonium salts, the rest mother liquor recycle to hydrolysis procedure; DL-mandelic acid refining, dissolve DL-mandelic acid coarse product into water, add active carbon to decolor, filtrate, crystal, centrifugation and drying to gain DL-mandelic acid finished product whose yield is high and cost is low.