The Fe3O4@SiO2 paramagnetic Janus particles with phenyl groups and amino groups segmented on two different sides were fabricated by the Pickering emulsion method. Then, the poly(ionic liquid)s were selectively modified onto the amino side via in situ induced ATRP polymerization. Different anions were introduced onto the poly(ionic liquid)s region by exchanging anions to adjust the wettability of the side. Meanwhile, after the PW12O403- anions were employed, the poly(ionic liquid)-modified Fe3O4@SiO2 Janus particles can be used as a catalytic solid emulsifier and degraded water-soluble dyes with the aid of stabilizing emulsion.