The invention discloses an epoxy resin dough moulding compound and a preparation method thereof. The epoxy resin dough moulding compound is prepared by evenly kneading 35-40 parts by mass of epoxy resin paste, 4-5 parts by mass of curing agent mixture and 65-70 parts by mass of chopped fiber, wherein the epoxy resin paste comprises the following components in parts by mass: 80-120 parts of epoxy resin, 5-10 parts of plasticizer, 4-8 parts of filler, 3-6 parts of mould release agent and 0.5-2 part(s) of coupling agent; the curing agent mixture comprises the following components in parts by mass: 4-7 parts of latent curing agent, 1-3 part(s) of accelerator and 6-10 parts of amine curing agent, and the length of the chopper fiber is one eighth to one half inch. Compared with the traditional method, the preparation method eliminates the curing process, and the dough moulding compound is prepared by adding modifying components and different curing systems into the epoxy resin. The method has the advantages of simple operation, high production efficiency, long working life and easy formation. Since the baking oven and other heating equipment are not needed, the method can reduce the energy consumption. Moreover, the method is applicable to fields of structural materials and composite materials with high requirements for insulation and electrical properties, and can be easily promoted and implemented.