The invention relates to a low-viscosity epoxy acrylate paint for an inner wall of a food can and a preparation method thereof. The preparation method comprises the following steps: 1) preparation of low-viscosity epoxy acrylate resin: adding bisphenols A epoxy resin and a catalyst into a reaction vessel, stirring and heating, adding pentaerythritol, keeping the temperature and carrying out reflux condensation so as to prepare pentaerythritol epoxy ester; cooling, dropwisely adding a mixture of the catalyst, a polymerization inhibitor and acrylic acid, carrying out a thermostatic reaction, cooling and discharging so as to prepare low-viscosity epoxy acrylate resin; adding a leveling agent and an antifoaming agent, stirring and uniformly mixing so as to obtain the low-viscosity epoxy acrylate paint for the inner wall of the food can. The invention has the following beneficial effects: pentaerythritol epoxy acrylate has a hyper-branched characteristic, has advantages of high degree of unsaturation, low viscosity and good adhesive force, is suitable for electron beam curing, and is non-toxic; and a cured film has properties such as high crosslinking density, excellent glossiness, flexibility, hardness, acid resistance, alkali resistance, water resistance and the like.