The invention relates to a preparation method for polyacrylic acid large-grain bead-shaped water absorbing resin, which is characterized by comprising the following steps: preparing any of toluene, cyclohexane or ortho-xylene and carbon tetrachloride into a mixed continuous phase; adding ethyl cellulose functioning as oil-soluble dispensing agent, stirring the ethyl cellulose to the mixed continuous phase and heating the mixture; evenly mixing a synthesized monomer with all components of an initiating agent and a cross linking agent; after the reaction is finished, cooling the mixture to roomtemperature; performing filtering, washing and vacuum drying to the mixture to obtain white bead-shaped water absorbing resin; and simultaneously reclaiming the solvent. The invention has the advantages that nitrogen does not need to be led in the reaction process, and acrylic acid (analytical reagent) does not need to be rectified and can be directly used, thereby the synthesis steps and the posttreatment process are simplified. If the dosage of the cross liking agent is small, the water absorption rate is large, but the formed grains have small strength and diameter are prone to agglomeration on surfaces; and if the dosage of the cross linking agent is large, the water absorption rate is correspondingly reduced, but the formed grains have improved strength and larger diameter.