A preparation method of a sulfonate flotation agent comprises the following steps that (1), paraffin-base or naphthenic-base distillate oil, oxidized paraffin and olein serve as raw materials to conduct sulfonation, acid oil subjected to sulfonation is subjected to standing for sedimentation, and the acid oil containing pure sulphonic acid on the upper layer and multisulfo-based sulfonic acid on the lower layer are separated; (2), the acid oil containing the pure sulphonic acid and the multisulfo-based sulfonic acid are neutralized into salt through sodium hydroxide aqueous solutions correspondingly; and (3) the neutralized sulphonate and multisulfo-based sulphonate are blended, and a product after blending is the sulfonate flotation agent.