The invention provides a dietary-fiber-rich farci cake which comprises fillings and a cake blank. The cake blank comprises, by weight, 20-26 parts of fresh eggs, 13-18 parts of salad oil, 25-30 partsof flour, 10-20 parts of flaxseed meal, 12-18 parts of white granulated sugar, 3-7 parts of sugar alcohol, 1-2 parts of cake oil, 1-2 parts of raising agents, 0.3-0.5 part of edible salt, 0.1-0.12 part of essence and 2-4 parts of cake modifying agents. The invention further provides a preparation method of the farci cake. According to the farci cake, the flaxseed meal partly replaces the flour toprepare the cake blank, the flaxseed meal and the cake modifying agents are compounded and used, the thickening stability of the cake modifying agents is enhanced, bonding properties of cake slurry are enhanced, supporting force of the cake slurry is improved, plasticity of the cake blank is improved, and the farci cake solves the problems that forming is difficult, and the fillings easily sink tothe bottom when the farci cake is made.