The present invention relates to a method for preparing graphene using the two-dimensional confined space between the layers of inorganic layered materials. Such method comprises the following steps: mix a soluble salt of a divalent metal ion M2+, a soluble salt of a trivalent metal ion M′3+, a soluble salt of a chain alkyl anion A− and a carbon source molecule C and dissolve them in deionized and CO2-eliminated water to prepare a mixed salt solution; mix the mixed salt solution with an alkali solution under nitrogen protection and subject them to reaction and crystallization under nitrogen, and filter the suspension obtained thereafter and wash the filter cake with deionized water until the pH of the filtrate is 7 to 7.5, and then dry the filter cake to obtain layered double hydroxides with an intercalated structure; under an inert atmosphere or a reducing atmosphere, calcinate the layered double hydroxides with an intercalated structure to provide a calcinated product; add the calcinated product into a hydrochloric acid solution for ultrasonic treatment, and separate the solution by centrifugation and wash the precipitate obtained by centrifugation with deionized water until the pH of the filtrate is 6.5 to 7 to obtain the graphene.