The invention provides a preparation method of a silicon-supported ion complexing agent. According to the invention, under the existence of an olefin metathesis catalyst, thiourea or mercapto compound containing ethylenically unsaturated substituent is subjected to a reaction with an organosiloxane monomer containing ethylenically unsaturated substituent, such that the silicon-supported ion complexing agent is prepared. The silicon-supported ion complexing agent is used in removing a homogeneous rhodium catalyst from a HNBR glue. Thiourea group can complex rhodium ions. Through centrifugal separation, the removal rate of rhodium in the glue can be higher than 95%.