The invention discloses a preparation method of a 
polyacrylonitrile chelating resin adsorbent. The method includes firstly, adding 
polyacrylonitrile microspheres to reaction solvents for immersion; secondly, adding 2-
aminothiazole which serves as a ligand and metallic 
sodium which serves as a catalytic agent to the swelling 
polyacrylonitrile microspheres for reaction under protection of 
nitrogen; and thirdly, using the reaction solvents to immerse modified polyacrylonitrile chelating resins, washing the modified polyacrylonitrile chelating resins until washing liquids are colorless, sequentially using deionized water, 
alcohol and diethyl ethers to wash the modified polyacrylonitrile chelating resins for a plurality of times, then using 
distilled water to wash the modified polyacrylonitrile chelating resins, sequentially performing alkali wash, 
water washing, 
acid washing and 
water washing, and 
drying the polyacrylonitrile chelating resins to constant weight at the temperature between 40 DEG C and 60 DEG C to obtain the polyacrylonitrile 
chelating resin adsorbent. The polyacrylonitrile 
chelating resin adsorbent prepared by the method can absorb Hg (II) ions in a higher selectivity mode.