The invention relates to a puffed kelp snow rice cracker and a preparation method thereof. The preparation method comprises the following steps of washing fresh kelp, then soaking to remove arsenic, removing fishy smell, further air-drying, cutting up, drying, and pulverizing to get kelp powder; weighing the kelp powder, millet flour and corn starch to prepare main materials, weighing sodium bicarbonate, soft sugar, common salt, chicken essence, baking powder and vanillin as auxiliary materials, and uniformly mixing to get mixed powder; wetting and pasting 90% of the mixed powder, and then mixing the pasted mixed powder with the remaining 10% of the mixed powder to prepare a cracker blank; and further drying the cracker blank, adjusting water content, puffing, spraying sugar, performing oil spraying treatment and packaging to get a finished product. The puffed kelp snow rice cracker disclosed by the invention has the advantages of unique flavor, crisp taste, abundant nutrition and easiness for digestion and absorption, and has the effects of strengthening stomach, enhancing immunologic function and the like. The preparation method has the advantages of scientific mixture ratio of the selected materials, reasonable process steps, simple process, strong operability and short production period, and is suitable for industrial production.