During the COVID-19 pandemic, the release of toxic disinfection by-products (DBPs) has increased due to the intensive, large-scale use of disinfectants. Halogenated benzoquinones (HBQs) are among the most toxic DBPs, but there is no rapid, convenient, and economical detection method. In this study, a novel PDIL/BDD-modified electrode was prepared in a mixed solvent of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) by electrochemical polymerization with a di-ionic ionic liquid containing alkenyl groups as the monomer. The electrochemical behavior of tetra-chloro- p -benzoquinone (TCBQ) on the modified electrode was studied. By studying the cyclic voltammetry behavior of TCBQ on the PDIL/BDD electrode, it was concluded that the electrode reactions of TCBQ included the reduction of TCBQ to TCBQH 2 (C1) and the reduction of bis-quinhydrone imidazole π-π type charge transfer complex to TCBQH 2 (C2). By studying the SWV responses of TCBQ in the concentration range of 1-100 ng/L on the PDIL/BDD electrode, it was found that the reduction peak current ( I pa ) had a linear relationship with the concentration. The electrochemical SWV technique was used to detect the concentration of trace TCBQ in water and is expected to be used for the detection of other HBQs in drinking water and swimming pool water.