Preparation method of bisphenol A liquid epoxy resin

Provided is a preparation method of bisphenol A liquid epoxy resin. The preparation method comprises dissolving bisphenol A and epichlorohydrin, and under the conditions of 45-65 DEG C, adding a cocatalyst and NaOH solution to perform etherification for 1-3h; under the conditions of 55-70 DEG C and absolute pressure of 15-25KPa, adding the NaOH solution dropwise; after a reaction is finished, removing water and excessive epichlorohydrin to obtain coarse epoxy resin; and utilizing an organic solvent to dissolve the coarse epoxy resin, and under the condition of 60-100 DEG C, adding NaOH solution to react for 1-4h, removing salt and waste polymer by washing, and removing the solvent to obtain the high-purity, low-organochlorine and low-viscosity bisphenol A liquid epoxy resin.