The invention relates to a preparation method for a multiple emulsion crosslinking agent. Raw materials are put in a reaction kettle, the preparation method comprises the following steps: (A) preparing chromium lactate aqueous solution, wherein chromium lactate accounts for 3 to 7 portions and the balance being deionized water; (B) preparing oil phase: adding white oil in the reaction kettle and then adding 1 to 3 portions of dehydrated sorbitol fatty acid ester and polyethyleneglycol respectively and white oil while stirring at a speed of 50 to 100rpm; (C) preparing water-in-oil emulsion: adding 4 to 7portions of the chromium lactate aqueous solution in the oil phase while stirring at a speed of 1,000 to 3,000rpm and then stirring continuously for 30min; (D) preparing continuous water phase: adding deionized water in the reaction kettle and then adding 1 to 2 portions of polyoxyethylene sorbitan monooleate while stirring at a speed of 50 to 100rpm; and (E) preparing the object substance: adding the water-in-oil emulsion in the continuous water phase in the proportion of 1:1 while stirring at a speed of 50 to 100rpm and then stirring continuously for 30min.