The invention relates to an epoxy resin composition for semiconductor packaging, and a preparation method thereof. The preparation method comprises the following steps: adding a curing agent phenolic resin, a curing accelerator, a mold lubricant, a fire retardant and a low stress modifier to a reaction kettle, carrying out hot melting mixing at 120-180DEG C, stirring until uniformity, cooling the obtained mixture to room temperature, crushing the cooled mixture, carrying out ball milling, and sieving the ball-milled mixture by a sieve; uniformly stirring the above obtained powder, epoxy resin, an inorganic filler, a coloring agent and a silane coupling agent in a high speed stirrer; and mixing and extruding the above obtained mixture in a double screw extruder, cooing the extruded mixture, and crushing the cooled mixture to obtain the epoxy resin composition for semiconductor packaging. The epoxy resin composition for semiconductor packaging has the advantages of increase of the yield in the packaging process, good mold release performance, great increase of the packaging frequency, and reduction of the incidence rate of pores in packaged bodies in packaging of semiconductor devices and integrated circuits.