The invention discloses a preparation method of epoxy resin modified emulsified asphalt. The preparation method comprises the steps of mixing epoxy resin with heated matrix asphalt, and then emulsifying according to a conventional asphalt emulsifying method and is characterized in that firstly, the epoxy modified emulsified asphalt can be obtained after only one-time emulsification process and noseparate waterborne processing for epoxy resin is required, so that processing procedures are reduced; secondly, epoxy resin has extremely-low viscosity when being heated to about 130 DEG C, thereby facilitating the uniformly dispersion of epoxy resin in the asphalt, so that the epoxy resin is added to reduce the viscosity of the asphalt, facilitate the implementation of emulsification, effectively reduce particle sizes of emulsion particles, and benefit stable storage of emulsion, film forming uniformity and uniform coating of aggregate in the mixing process; thirdly, single emulsion particleis a mixture of asphalt and epoxy, and the demulsification process of the emulsion particles is performed at the same time, so that the epoxy resin subjected to demulsification and film formation canbe uniformly distributed in the asphalt, the modification effect is improved and more excellent performance can be obtained.