The invention relates to a method for preparing a seaweed gel face mask. Seaweed gel is used as a raw material to be prepared into face mask liquid by adding brown algae polyphenol, fucoxanthin, sodium hyaluronate, honey, deionized water, a viscosity modifier, a functional extract component, a soothing component, and a PH adjusting component, standing is conducted, then a mask sheet is soaked inside, and finally the seaweed gel face mask is prepared through vacuum bag sealing and autoclaving. The seaweed gel face mask is good in moisturizing and moisture preserving effects and has freckle removing, anti-wrinkle, and anti-aging functions, the skin is kept refreshing, elastic, and shiny, meanwhile various chemical additives are not added, and the manufacturing technology of the face mask issimple and naturally non-stimulating.